diff --git a/src/plugin_system/store_manager.py b/src/plugin_system/store_manager.py
index d547fbf0..5a774056 100644
--- a/src/plugin_system/store_manager.py
+++ b/src/plugin_system/store_manager.py
@@ -21,6 +21,8 @@ from pathlib import Path
 from typing import List, Dict, Optional, Any, Tuple
 import logging
 
+from urllib.parse import urlparse
+
 from src.common.permission_utils import sudo_remove_directory
 
 try:
@@ -356,7 +358,8 @@ class PluginStoreManager:
         # Extract owner/repo from URL
         try:
             # Handle different URL formats
-            if 'github.com' in repo_url:
+            _parsed_url = urlparse(repo_url)
+            if _parsed_url.hostname in ('github.com', 'www.github.com'):
                 parts = repo_url.strip('/').split('/')
                 if len(parts) >= 2:
                     owner = parts[-2]
@@ -518,9 +521,10 @@ class PluginStoreManager:
             # Try to find plugins.json in common locations
             # First try root directory
             registry_urls = []
-            
+
             # Extract owner/repo from URL
-            if 'github.com' in repo_url:
+            _parsed_repo_url = urlparse(repo_url)
+            if _parsed_repo_url.hostname in ('github.com', 'www.github.com'):
                 parts = repo_url.split('/')
                 if len(parts) >= 2:
                     owner = parts[-2]
@@ -775,7 +779,8 @@ class PluginStoreManager:
         try:
             # Convert repo URL to raw content URL
             # https://github.com/user/repo -> https://raw.githubusercontent.com/user/repo/branch/manifest.json
-            if 'github.com' in repo_url:
+            _parsed_manifest_url = urlparse(repo_url)
+            if _parsed_manifest_url.hostname in ('github.com', 'www.github.com'):
                 # Handle different URL formats
                 repo_url = repo_url.rstrip('/')
                 if repo_url.endswith('.git'):
diff --git a/web_interface/app.py b/web_interface/app.py
index c87a7f21..1bccd49c 100644
--- a/web_interface/app.py
+++ b/web_interface/app.py
@@ -204,24 +204,12 @@ def serve_plugin_asset(plugin_id, filename):
         # Use send_from_directory to serve the file
         return send_from_directory(str(assets_dir), filename, mimetype=content_type)
         
-    except Exception as e:
-        # Log the exception with full traceback server-side
-        import traceback
+    except Exception:
         app.logger.exception('Error serving plugin asset file')
-        
-        # Return generic error message to client (avoid leaking internal details)
-        # Only include detailed error information when in debug mode
-        if app.debug:
-            return jsonify({
-                'status': 'error',
-                'message': str(e),
-                'traceback': traceback.format_exc()
-            }), 500
-        else:
-            return jsonify({
-                'status': 'error',
-                'message': 'Internal server error'
-            }), 500
+        return jsonify({
+            'status': 'error',
+            'message': 'Internal server error'
+        }), 500
 
 # Prime psutil CPU measurement once at startup so interval=None returns a real value
 try:
@@ -342,35 +330,25 @@ def not_found_error(error):
 @app.errorhandler(500)
 def internal_error(error):
     """Handle 500 errors."""
-    import traceback
-    error_details = traceback.format_exc()
-    
-    # Log the error
     import logging
     logger = logging.getLogger('web_interface')
-    logger.error(f"Internal server error: {error}", exc_info=True)
-    
-    # Return user-friendly error (hide internal details in production)
+    logger.error("Internal server error", exc_info=True)
     return jsonify({
         'status': 'error',
         'error_code': 'INTERNAL_ERROR',
-        'message': 'An internal error occurred',
-        'details': error_details if app.debug else None
+        'message': 'An internal error occurred; see logs for details',
     }), 500
 
 @app.errorhandler(Exception)
 def handle_exception(error):
     """Handle all unhandled exceptions."""
-    import traceback
     import logging
     logger = logging.getLogger('web_interface')
-    logger.error(f"Unhandled exception: {error}", exc_info=True)
-    
+    logger.error("Unhandled exception", exc_info=True)
     return jsonify({
         'status': 'error',
         'error_code': 'UNKNOWN_ERROR',
-        'message': str(error) if app.debug else 'An error occurred',
-        'details': traceback.format_exc() if app.debug else None
+        'message': 'An error occurred; see logs for details',
     }), 500
 
 # Captive portal redirect middleware
@@ -492,7 +470,8 @@ def system_status_generator():
             }
             yield status
         except Exception as e:
-            yield {'error': str(e)}
+            app.logger.error("SSE generator error", exc_info=True)
+            yield {'error': 'An error occurred; see server logs'}
         time.sleep(10)  # Update every 10 seconds (reduced frequency for better performance)
 
 # Display preview generator for SSE
@@ -555,7 +534,8 @@ def display_preview_generator():
                 }
                 
         except Exception as e:
-            yield {'error': str(e)}
+            app.logger.error("SSE generator error", exc_info=True)
+            yield {'error': 'An error occurred; see server logs'}
         
         time.sleep(1.0)  # Check once per second — halves PIL encode overhead vs 0.5s
 
@@ -598,17 +578,19 @@ def logs_generator():
             except subprocess.TimeoutExpired:
                 # Timeout - just skip this update
                 pass
-            except Exception as e:
+            except Exception:
+                app.logger.error("Error running journalctl", exc_info=True)
                 error_data = {
                     'timestamp': time.time(),
-                    'logs': f'Error running journalctl: {str(e)}'
+                    'logs': 'Error running journalctl; see server logs'
                 }
                 yield error_data
 
-        except Exception as e:
+        except Exception:
+            app.logger.error("Unexpected error in logs generator", exc_info=True)
             error_data = {
                 'timestamp': time.time(),
-                'logs': f'Unexpected error in logs generator: {str(e)}'
+                'logs': 'Unexpected error in logs generator; see server logs'
             }
             yield error_data
 
diff --git a/web_interface/blueprints/api_v3.py b/web_interface/blueprints/api_v3.py
index 3e11050b..2222aa84 100644
--- a/web_interface/blueprints/api_v3.py
+++ b/web_interface/blueprints/api_v3.py
@@ -211,7 +211,8 @@ def get_main_config():
         config = api_v3.config_manager.load_config()
         return jsonify({'status': 'success', 'data': config})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/config/schedule', methods=['GET'])
 def get_schedule_config():
@@ -231,7 +232,7 @@ def get_schedule_config():
     except Exception as e:
         return error_response(
             ErrorCode.CONFIG_LOAD_FAILED,
-            f"Error loading schedule configuration: {str(e)}",
+            "An error occurred; see logs for details",
             status_code=500
         )
 
@@ -406,8 +407,8 @@ def save_schedule_config():
         logging.error(error_msg)
         return error_response(
             ErrorCode.CONFIG_SAVE_FAILED,
-            f"Error saving schedule configuration: {str(e)}",
-            details=traceback.format_exc(),
+            "An error occurred; see logs for details",
+
             status_code=500
         )
 
@@ -455,14 +456,14 @@ def get_dim_schedule_config():
         logging.error(f"[DIM SCHEDULE] Error reading config file: {e}", exc_info=True)
         return error_response(
             ErrorCode.CONFIG_LOAD_FAILED,
-            f"Error reading configuration file: {str(e)}",
+            "An error occurred; see logs for details",
             status_code=500
         )
     except Exception as e:
         logging.error(f"[DIM SCHEDULE] Unexpected error loading config: {e}", exc_info=True)
         return error_response(
             ErrorCode.CONFIG_LOAD_FAILED,
-            f"Unexpected error loading dim schedule configuration: {str(e)}",
+            "An error occurred; see logs for details",
             status_code=500
         )
 
@@ -627,8 +628,8 @@ def save_dim_schedule_config():
         logging.error(error_msg)
         return error_response(
             ErrorCode.CONFIG_SAVE_FAILED,
-            f"Error saving dim schedule configuration: {str(e)}",
-            details=traceback.format_exc(),
+            "An error occurred; see logs for details",
+
             status_code=500
         )
 
@@ -1049,7 +1050,7 @@ def save_main_config():
         return error_response(
             ErrorCode.CONFIG_SAVE_FAILED,
             f"Error saving configuration: {e}",
-            details=traceback.format_exc(),
+
             status_code=500
         )
 
@@ -1063,7 +1064,8 @@ def get_secrets_config():
         config = api_v3.config_manager.get_raw_file_content('secrets')
         return jsonify({'status': 'success', 'data': config})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/config/raw/main', methods=['POST'])
 def save_raw_main_config():
@@ -1082,7 +1084,8 @@ def save_raw_main_config():
 
         return jsonify({'status': 'success', 'message': 'Main configuration saved successfully'})
     except json.JSONDecodeError as e:
-        return jsonify({'status': 'error', 'message': f'Invalid JSON: {str(e)}'}), 400
+        logger.error('Invalid JSON', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'Invalid JSON in request body'}), 400
     except Exception as e:
         import logging
         import traceback
@@ -1094,22 +1097,22 @@ def save_raw_main_config():
 
         # Extract more specific error message if it's a ConfigError
         if isinstance(e, ConfigError):
-            error_message = str(e)
+            error_message = 'An error occurred; see logs for details'
             if hasattr(e, 'config_path') and e.config_path:
                 error_message = f"{error_message} (config_path: {e.config_path})"
             return error_response(
                 ErrorCode.CONFIG_SAVE_FAILED,
                 error_message,
-                details=traceback.format_exc(),
+
                 context={'config_path': e.config_path} if hasattr(e, 'config_path') and e.config_path else None,
                 status_code=500
             )
         else:
-            error_message = str(e) if str(e) else "An unexpected error occurred while saving the configuration"
+            error_message = 'An error occurred; see logs for details'
             return error_response(
                 ErrorCode.UNKNOWN_ERROR,
                 error_message,
-                details=traceback.format_exc(),
+
                 status_code=500
             )
 
@@ -1133,7 +1136,8 @@ def save_raw_secrets_config():
 
         return jsonify({'status': 'success', 'message': 'Secrets configuration saved successfully'})
     except json.JSONDecodeError as e:
-        return jsonify({'status': 'error', 'message': f'Invalid JSON: {str(e)}'}), 400
+        logger.error('Invalid JSON', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'Invalid JSON in request body'}), 400
     except Exception as e:
         import logging
         import traceback
@@ -1146,11 +1150,11 @@ def save_raw_secrets_config():
         # Extract more specific error message if it's a ConfigError
         if isinstance(e, ConfigError):
             # ConfigError has a message attribute and may have context
-            error_message = str(e)
+            error_message = 'An error occurred; see logs for details'
             if hasattr(e, 'config_path') and e.config_path:
                 error_message = f"{error_message} (config_path: {e.config_path})"
         else:
-            error_message = str(e) if str(e) else "An unexpected error occurred while saving the configuration"
+            error_message = 'An error occurred; see logs for details'
 
         return jsonify({'status': 'error', 'message': error_message}), 500
 
@@ -1239,7 +1243,8 @@ def get_system_status():
 
         return jsonify({'status': 'success', 'data': status})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/health', methods=['GET'])
 def get_health():
@@ -1283,7 +1288,7 @@ def get_health():
             health_status['checks']['config_file'] = {
                 'status': 'error',
                 'readable': False,
-                'error': str(e)
+                'error': 'see logs for details'
             }
 
         # Check plugin system
@@ -1302,7 +1307,7 @@ def get_health():
         except Exception as e:
             health_status['checks']['plugin_system'] = {
                 'status': 'error',
-                'error': str(e)
+                'error': 'see logs for details'
             }
 
         # Check hardware connectivity (if display manager available)
@@ -1324,7 +1329,7 @@ def get_health():
         except Exception as e:
             health_status['checks']['hardware'] = {
                 'status': 'unknown',
-                'error': str(e)
+                'error': 'see logs for details'
             }
 
         # Determine overall health
@@ -1340,7 +1345,7 @@ def get_health():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': str(e),
+            'message': 'An error occurred; see logs for details',
             'data': {'status': 'unhealthy'}
         }), 500
 
@@ -1658,7 +1663,8 @@ def get_display_current():
         }
         return jsonify({'status': 'success', 'data': display_data})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/display/on-demand/status', methods=['GET'])
 def get_on_demand_status():
@@ -1683,9 +1689,8 @@ def get_on_demand_status():
     except Exception as exc:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_on_demand_status: {exc}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(exc)}), 500
+        logger.error('Error in get_on_demand_status', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/display/on-demand/start', methods=['POST'])
 def start_on_demand_display():
@@ -1789,9 +1794,8 @@ def start_on_demand_display():
     except Exception as exc:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in start_on_demand_display: {exc}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(exc)}), 500
+        logger.error('Error in start_on_demand_display', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/display/on-demand/stop', methods=['POST'])
 def stop_on_demand_display():
@@ -1828,9 +1832,8 @@ def stop_on_demand_display():
     except Exception as exc:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in stop_on_demand_display: {exc}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(exc)}), 500
+        logger.error('Error in stop_on_demand_display', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/installed', methods=['GET'])
 def get_installed_plugins():
@@ -1960,9 +1963,8 @@ def get_installed_plugins():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_installed_plugins: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e), 'details': error_details}), 500
+        logger.error('Error in get_installed_plugins', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/health', methods=['GET'])
 def get_plugin_health():
@@ -1989,9 +1991,8 @@ def get_plugin_health():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_plugin_health: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_plugin_health', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/health/<plugin_id>', methods=['GET'])
 def get_plugin_health_single(plugin_id):
@@ -2017,9 +2018,8 @@ def get_plugin_health_single(plugin_id):
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_plugin_health_single: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_plugin_health_single', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/health/<plugin_id>/reset', methods=['POST'])
 def reset_plugin_health(plugin_id):
@@ -2045,9 +2045,8 @@ def reset_plugin_health(plugin_id):
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in reset_plugin_health: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in reset_plugin_health', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/metrics', methods=['GET'])
 def get_plugin_metrics():
@@ -2074,9 +2073,8 @@ def get_plugin_metrics():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_plugin_metrics: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_plugin_metrics', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/metrics/<plugin_id>', methods=['GET'])
 def get_plugin_metrics_single(plugin_id):
@@ -2102,9 +2100,8 @@ def get_plugin_metrics_single(plugin_id):
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_plugin_metrics_single: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_plugin_metrics_single', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/metrics/<plugin_id>/reset', methods=['POST'])
 def reset_plugin_metrics(plugin_id):
@@ -2130,9 +2127,8 @@ def reset_plugin_metrics(plugin_id):
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in reset_plugin_metrics: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in reset_plugin_metrics', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/limits/<plugin_id>', methods=['GET', 'POST'])
 def manage_plugin_limits(plugin_id):
@@ -2188,9 +2184,8 @@ def manage_plugin_limits(plugin_id):
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in manage_plugin_limits: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in manage_plugin_limits', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/toggle', methods=['POST'])
 def toggle_plugin():
@@ -2674,18 +2669,13 @@ def update_plugin():
             # JSON request
             data, error = validate_request_json(['plugin_id'])
             if error:
-                # Log what we received for debugging
-                print(f"[UPDATE] JSON validation failed. Content-Type: {content_type}")
-                print(f"[UPDATE] Request data: {request.data}")
-                print(f"[UPDATE] Request form: {request.form.to_dict()}")
+                logger.debug("[UPDATE] JSON validation failed. Content-Type: %s", content_type)
                 return error
         else:
             # Form data or query string
             plugin_id = request.args.get('plugin_id') or request.form.get('plugin_id')
             if not plugin_id:
-                print(f"[UPDATE] Missing plugin_id. Content-Type: {content_type}")
-                print(f"[UPDATE] Query args: {request.args.to_dict()}")
-                print(f"[UPDATE] Form data: {request.form.to_dict()}")
+                logger.debug("[UPDATE] Missing plugin_id. Content-Type: %s", content_type)
                 return error_response(
                     ErrorCode.INVALID_INPUT,
                     'plugin_id required',
@@ -2859,7 +2849,7 @@ def update_plugin():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"[UPDATE] Exception in update_plugin endpoint: {str(e)}")
+        logger.error("Unhandled exception in update endpoint", exc_info=True)
         print(f"[UPDATE] Traceback: {error_details}")
         
         from src.web_interface.errors import WebInterfaceError
@@ -3158,9 +3148,8 @@ def install_plugin():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in install_plugin: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in install_plugin', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/install-from-url', methods=['POST'])
 def install_plugin_from_url():
@@ -3216,9 +3205,8 @@ def install_plugin_from_url():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in install_plugin_from_url: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in install_plugin_from_url', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/registry-from-url', methods=['POST'])
 def get_registry_from_url():
@@ -3251,9 +3239,8 @@ def get_registry_from_url():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_registry_from_url: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_registry_from_url', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/saved-repositories', methods=['GET'])
 def get_saved_repositories():
@@ -3267,9 +3254,8 @@ def get_saved_repositories():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_saved_repositories: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_saved_repositories', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/saved-repositories', methods=['POST'])
 def add_saved_repository():
@@ -3301,9 +3287,8 @@ def add_saved_repository():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in add_saved_repository: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in add_saved_repository', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/saved-repositories', methods=['DELETE'])
 def remove_saved_repository():
@@ -3334,9 +3319,8 @@ def remove_saved_repository():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in remove_saved_repository: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in remove_saved_repository', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/store/list', methods=['GET'])
 def list_plugin_store():
@@ -3390,9 +3374,8 @@ def list_plugin_store():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in list_plugin_store: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in list_plugin_store', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/store/github-status', methods=['GET'])
 def get_github_auth_status():
@@ -3444,9 +3427,8 @@ def get_github_auth_status():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_github_auth_status: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_github_auth_status', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/store/refresh', methods=['POST'])
 def refresh_plugin_store():
@@ -3474,9 +3456,8 @@ def refresh_plugin_store():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in refresh_plugin_store: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in refresh_plugin_store', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 def deep_merge(base_dict, update_dict):
     """
@@ -4760,18 +4741,8 @@ def save_plugin_config():
         if plugin_id not in current_config:
             current_config[plugin_id] = {}
 
-        # Debug logging for live_priority before merge
-        if plugin_id == 'football-scoreboard':
-            print(f"[DEBUG] Before merge - current NFL live_priority: {current_config[plugin_id].get('nfl', {}).get('live_priority')}")
-            print(f"[DEBUG] Before merge - regular_config NFL live_priority: {regular_config.get('nfl', {}).get('live_priority')}")
-
         current_config[plugin_id] = deep_merge(current_config[plugin_id], regular_config)
 
-        # Debug logging for live_priority after merge
-        if plugin_id == 'football-scoreboard':
-            print(f"[DEBUG] After merge - NFL live_priority: {current_config[plugin_id].get('nfl', {}).get('live_priority')}")
-            print(f"[DEBUG] After merge - NCAA FB live_priority: {current_config[plugin_id].get('ncaa_fb', {}).get('live_priority')}")
-
         # Deep merge plugin secrets in secrets config
         if secrets_config:
             if plugin_id not in current_secrets:
@@ -4807,11 +4778,11 @@ def save_plugin_config():
                 # Log the error but don't fail the entire config save
                 import os
                 secrets_path = api_v3.config_manager.secrets_path
-                logger.error(f"Error saving secrets config for {plugin_id}: {e}", exc_info=True)
+                logger.error("Error saving secrets config for %s (path=%s)", plugin_id, secrets_path, exc_info=True)
                 # Return error response with more context
                 return error_response(
                     ErrorCode.CONFIG_SAVE_FAILED,
-                    f"Failed to save secrets configuration: {str(e)} (config_path={secrets_path})",
+                    "Failed to save secrets configuration; see logs for details",
                     status_code=500
                 )
 
@@ -4927,9 +4898,8 @@ def get_plugin_schema():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in get_plugin_schema: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in get_plugin_schema', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/config/reset', methods=['POST'])
 def reset_plugin_config():
@@ -5041,9 +5011,8 @@ def reset_plugin_config():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in reset_plugin_config: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in reset_plugin_config', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/action', methods=['POST'])
 def execute_plugin_action():
@@ -5058,10 +5027,8 @@ def execute_plugin_action():
             logger.error(f"Error parsing JSON in execute_plugin_action: {e}")
             return jsonify({
                 'status': 'error', 
-                'message': f'Invalid JSON in request: {str(e)}',
-                'content_type': request.content_type,
-                'data': request.data.decode('utf-8', errors='ignore')[:200]
-            }), 400
+                'message': 'Invalid JSON in request body',
+                'content_type': request.content_type }), 400
         
         plugin_id = data.get('plugin_id')
         action_id = data.get('action_id')
@@ -5305,10 +5272,9 @@ sys.exit(proc.returncode)
                             import traceback
                             error_details = traceback.format_exc()
                             print(f"Error executing action step 1: {e}")
-                            print(error_details)
                             return jsonify({
                                 'status': 'error',
-                                'message': f'Error executing action: {str(e)}'
+                                'message': 'An error occurred; see logs for details'
                             }), 500
                     else:
                         # Simple script execution
@@ -5359,9 +5325,8 @@ sys.exit(proc.returncode)
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in execute_plugin_action: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in execute_plugin_action', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/authenticate/spotify', methods=['POST'])
 def authenticate_spotify():
@@ -5494,18 +5459,16 @@ sys.exit(proc.returncode)
                 import traceback
                 error_details = traceback.format_exc()
                 print(f"Error getting Spotify auth URL: {e}")
-                print(error_details)
                 return jsonify({
                     'status': 'error',
-                    'message': f'Error generating authorization URL: {str(e)}'
+                    'message': 'An error occurred; see logs for details'
                 }), 500
 
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in authenticate_spotify: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in authenticate_spotify', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/authenticate/ytm', methods=['POST'])
 def authenticate_ytm():
@@ -5556,9 +5519,8 @@ def authenticate_ytm():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in authenticate_ytm: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in authenticate_ytm', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/fonts/catalog', methods=['GET'])
 def get_fonts_catalog():
@@ -5653,7 +5615,7 @@ def get_fonts_catalog():
 
         return jsonify({'status': 'success', 'data': {'catalog': catalog}})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/fonts/tokens', methods=['GET'])
 def get_font_tokens():
@@ -5671,7 +5633,8 @@ def get_font_tokens():
         }
         return jsonify({'status': 'success', 'data': {'tokens': tokens}})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/fonts/overrides', methods=['GET'])
 def get_fonts_overrides():
@@ -5682,7 +5645,8 @@ def get_fonts_overrides():
         overrides = {}
         return jsonify({'status': 'success', 'data': {'overrides': overrides}})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/fonts/overrides', methods=['POST'])
 def save_fonts_overrides():
@@ -5695,7 +5659,8 @@ def save_fonts_overrides():
         # This would integrate with the actual font system
         return jsonify({'status': 'success', 'message': 'Font overrides saved'})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/fonts/overrides/<element_key>', methods=['DELETE'])
 def delete_font_override(element_key):
@@ -5704,7 +5669,8 @@ def delete_font_override(element_key):
         # This would integrate with the actual font system
         return jsonify({'status': 'success', 'message': f'Font override for {element_key} deleted'})
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/fonts/upload', methods=['POST'])
 def upload_font():
@@ -5768,7 +5734,8 @@ def upload_font():
             'path': f'assets/fonts/{safe_filename}'
         })
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 
 @api_v3.route('/fonts/preview', methods=['GET'])
@@ -5912,7 +5879,8 @@ def get_font_preview() -> tuple[Response, int] | Response:
             }
         })
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 
 @api_v3.route('/fonts/<font_family>', methods=['DELETE'])
@@ -5999,7 +5967,8 @@ def delete_font(font_family: str) -> tuple[Response, int] | Response:
             'message': f'Font {deleted_filename} deleted successfully'
         })
     except Exception as e:
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 
 @api_v3.route('/plugins/assets/upload', methods=['POST'])
@@ -6147,7 +6116,8 @@ def upload_plugin_asset():
 
     except Exception as e:
         import traceback
-        return jsonify({'status': 'error', 'message': str(e), 'traceback': traceback.format_exc()}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/of-the-day/json/upload', methods=['POST'])
 def upload_of_the_day_json():
@@ -6206,7 +6176,7 @@ def upload_of_the_day_json():
             except json.JSONDecodeError as e:
                 return jsonify({
                     'status': 'error',
-                    'message': f'Invalid JSON in {file.filename}: {str(e)}'
+                    'message': 'Invalid JSON in request body'
                 }), 400
             except UnicodeDecodeError:
                 return jsonify({
@@ -6297,7 +6267,8 @@ def upload_of_the_day_json():
 
     except Exception as e:
         import traceback
-        return jsonify({'status': 'error', 'message': str(e), 'traceback': traceback.format_exc()}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/of-the-day/json/delete', methods=['POST'])
 def delete_of_the_day_json():
@@ -6344,7 +6315,8 @@ def delete_of_the_day_json():
 
     except Exception as e:
         import traceback
-        return jsonify({'status': 'error', 'message': str(e), 'traceback': traceback.format_exc()}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/<plugin_id>/static/<path:file_path>', methods=['GET'])
 def serve_plugin_static(plugin_id, file_path):
@@ -6390,7 +6362,8 @@ def serve_plugin_static(plugin_id, file_path):
 
     except Exception as e:
         import traceback
-        return jsonify({'status': 'error', 'message': str(e), 'traceback': traceback.format_exc()}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 
 @api_v3.route('/plugins/calendar/upload-credentials', methods=['POST'])
@@ -6473,9 +6446,8 @@ def upload_calendar_credentials():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in upload_calendar_credentials: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in upload_calendar_credentials', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/assets/delete', methods=['POST'])
 def delete_plugin_asset():
@@ -6518,7 +6490,8 @@ def delete_plugin_asset():
 
     except Exception as e:
         import traceback
-        return jsonify({'status': 'error', 'message': str(e), 'traceback': traceback.format_exc()}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/plugins/assets/list', methods=['GET'])
 def list_plugin_assets():
@@ -6546,7 +6519,8 @@ def list_plugin_assets():
 
     except Exception as e:
         import traceback
-        return jsonify({'status': 'error', 'message': str(e), 'traceback': traceback.format_exc()}), 500
+        logger.error('Unhandled exception', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/logs', methods=['GET'])
 def get_logs():
@@ -6582,7 +6556,7 @@ def get_logs():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': f'Error fetching logs: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 # Multi-Display Sync Endpoints
@@ -6649,7 +6623,7 @@ def get_wifi_status():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': f'Error getting WiFi status: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/wifi/scan', methods=['GET'])
@@ -6697,7 +6671,8 @@ def scan_wifi_networks():
 
         return jsonify(response_data)
     except Exception as e:
-        error_message = f'Error scanning WiFi networks: {str(e)}'
+        logger.error("Error scanning WiFi networks", exc_info=True)
+        error_message = 'An error occurred while scanning WiFi networks; see logs for details'
 
         # Provide more specific error messages for common issues
         error_str = str(e).lower()
@@ -6773,7 +6748,7 @@ def connect_wifi():
         logger.error(f"Error connecting to WiFi: {e}\n{traceback.format_exc()}")
         return jsonify({
             'status': 'error',
-            'message': f'Error connecting to WiFi: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/wifi/disconnect', methods=['POST'])
@@ -6802,7 +6777,7 @@ def disconnect_wifi():
         logger.error(f"Error disconnecting from WiFi: {e}\n{traceback.format_exc()}")
         return jsonify({
             'status': 'error',
-            'message': f'Error disconnecting from WiFi: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/wifi/ap/enable', methods=['POST'])
@@ -6827,7 +6802,7 @@ def enable_ap_mode():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': f'Error enabling AP mode: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/wifi/ap/disable', methods=['POST'])
@@ -6852,7 +6827,7 @@ def disable_ap_mode():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': f'Error disabling AP mode: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/wifi/ap/auto-enable', methods=['GET'])
@@ -6873,7 +6848,7 @@ def get_auto_enable_ap_mode():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': f'Error getting auto-enable setting: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/wifi/ap/auto-enable', methods=['POST'])
@@ -6905,7 +6880,7 @@ def set_auto_enable_ap_mode():
     except Exception as e:
         return jsonify({
             'status': 'error',
-            'message': f'Error setting auto-enable: {str(e)}'
+            'message': 'An error occurred; see logs for details'
         }), 500
 
 @api_v3.route('/cache/list', methods=['GET'])
@@ -6931,9 +6906,8 @@ def list_cache_files():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in list_cache_files: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in list_cache_files', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 @api_v3.route('/cache/delete', methods=['POST'])
 def delete_cache_file():
@@ -6960,9 +6934,8 @@ def delete_cache_file():
     except Exception as e:
         import traceback
         error_details = traceback.format_exc()
-        print(f"Error in delete_cache_file: {str(e)}")
-        print(error_details)
-        return jsonify({'status': 'error', 'message': str(e)}), 500
+        logger.error('Error in delete_cache_file', exc_info=True)
+        return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details'}), 500
 
 
 # =============================================================================
@@ -6985,7 +6958,6 @@ def get_error_summary():
         return error_response(
             error_code=ErrorCode.SYSTEM_ERROR,
             message="Failed to retrieve error summary",
-            details=str(e),
             status_code=500
         )
 
@@ -7009,7 +6981,6 @@ def get_plugin_errors(plugin_id):
         return error_response(
             error_code=ErrorCode.SYSTEM_ERROR,
             message=f"Failed to retrieve health for plugin {plugin_id}",
-            details=str(e),
             status_code=500
         )
 
@@ -7063,7 +7034,6 @@ def clear_old_errors():
         return error_response(
             error_code=ErrorCode.SYSTEM_ERROR,
             message="Failed to clear old errors",
-            details=str(e),
             status_code=500
         )
 
diff --git a/web_interface/blueprints/pages_v3.py b/web_interface/blueprints/pages_v3.py
index 1215b241..bc3a1e81 100644
--- a/web_interface/blueprints/pages_v3.py
+++ b/web_interface/blueprints/pages_v3.py
@@ -84,10 +84,11 @@ def load_partial(partial_name):
         elif partial_name == 'operation-history':
             return _load_operation_history_partial()
         else:
-            return f"Partial '{partial_name}' not found", 404
+            return f"Partial '{escape(partial_name)}' not found", 404
 
     except Exception as e:
-        return f"Error loading partial '{partial_name}': {str(e)}", 500
+        logger.error("Error loading partial %s", partial_name, exc_info=True)
+        return "Error loading partial", 500
 
 
 @pages_v3.route('/partials/plugin-config/<plugin_id>')
@@ -95,8 +96,9 @@ def load_plugin_config_partial(plugin_id):
     """Load plugin configuration partial via HTMX - server-side rendered form"""
     try:
         return _load_plugin_config_partial(plugin_id)
-    except Exception as e:
-        return f'<div class="text-red-500 p-4">Error loading plugin config: {escape(str(e))}</div>', 500
+    except Exception:
+        logger.error("Error loading plugin config partial for %s", plugin_id, exc_info=True)
+        return '<div class="text-red-500 p-4">Error loading plugin config; see logs for details</div>', 500
 
 def _load_overview_partial():
     """Load overview partial with system stats"""
@@ -107,7 +109,8 @@ def _load_overview_partial():
             return render_template('v3/partials/overview.html',
                                  main_config=main_config)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_general_partial():
     """Load general settings partial"""
@@ -117,7 +120,8 @@ def _load_general_partial():
             return render_template('v3/partials/general.html',
                                  main_config=main_config)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_display_partial():
     """Load display settings partial"""
@@ -127,7 +131,8 @@ def _load_display_partial():
             return render_template('v3/partials/display.html',
                                  main_config=main_config)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_durations_partial():
     """Load display durations partial"""
@@ -137,7 +142,8 @@ def _load_durations_partial():
             return render_template('v3/partials/durations.html',
                                  main_config=main_config)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_schedule_partial():
     """Load schedule settings partial"""
@@ -153,7 +159,8 @@ def _load_schedule_partial():
                                  dim_schedule_config=dim_schedule_config,
                                  normal_brightness=normal_brightness)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 
 def _load_weather_partial():
@@ -164,7 +171,8 @@ def _load_weather_partial():
             return render_template('v3/partials/weather.html',
                                  main_config=main_config)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_stocks_partial():
     """Load stocks configuration partial"""
@@ -174,7 +182,8 @@ def _load_stocks_partial():
             return render_template('v3/partials/stocks.html',
                                  main_config=main_config)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_plugins_partial():
     """Load plugins management partial"""
@@ -208,7 +217,7 @@ def _load_plugins_partial():
                             plugin_info.update(fresh_manifest)
                         except Exception as e:
                             # If we can't read the fresh manifest, use the cached one
-                            print(f"Warning: Could not read fresh manifest for {plugin_id}: {e}")
+                            logger.warning("Could not read fresh manifest for {plugin_id}")
 
                     # Get enabled status from config (source of truth)
                     # Read from config file first, fall back to plugin instance if config doesn't have the key
@@ -256,12 +265,13 @@ def _load_plugins_partial():
                         'branch': branch
                     })
             except Exception as e:
-                print(f"Error loading plugin data: {e}")
+                logger.error("Error loading plugin data", exc_info=True)
 
         return render_template('v3/partials/plugins.html',
                              plugins=plugins_data)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_fonts_partial():
     """Load fonts management partial"""
@@ -271,14 +281,16 @@ def _load_fonts_partial():
         return render_template('v3/partials/fonts.html',
                              fonts=fonts_data)
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_logs_partial():
     """Load logs viewer partial"""
     try:
         return render_template('v3/partials/logs.html')
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_raw_json_partial():
     """Load raw JSON editor partial"""
@@ -295,14 +307,16 @@ def _load_raw_json_partial():
                                  main_config_path=pages_v3.config_manager.get_config_path(),
                                  secrets_config_path=pages_v3.config_manager.get_secrets_path())
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_backup_restore_partial():
     """Load backup & restore partial."""
     try:
         return render_template('v3/partials/backup_restore.html')
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 @pages_v3.route('/setup')
 def captive_setup():
@@ -314,21 +328,24 @@ def _load_wifi_partial():
     try:
         return render_template('v3/partials/wifi.html')
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_cache_partial():
     """Load cache management partial"""
     try:
         return render_template('v3/partials/cache.html')
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 def _load_operation_history_partial():
     """Load operation history partial"""
     try:
         return render_template('v3/partials/operation_history.html')
     except Exception as e:
-        return f"Error: {str(e)}", 500
+        logger.error("Error loading partial", exc_info=True)
+        return "Error loading partial", 500
 
 
 def _load_plugin_config_partial(plugin_id):
@@ -336,6 +353,11 @@ def _load_plugin_config_partial(plugin_id):
     Load plugin configuration partial - server-side rendered form.
     This replaces the client-side generateConfigForm() JavaScript.
     """
+    import re as _re
+    # Reject plugin IDs containing path-traversal characters before any filesystem use
+    if not _re.match(r'^[a-zA-Z0-9_\-.:]+$', plugin_id or ''):
+        return '<div class="text-red-500 p-4">Invalid plugin ID</div>', 400
+
     try:
         if not pages_v3.plugin_manager:
             return '<div class="text-red-500 p-4">Plugin manager not available</div>', 500
@@ -394,7 +416,7 @@ def _load_plugin_config_partial(plugin_id):
                                         if new_images:
                                             config['images'] = config.get('images', []) + new_images
                             except Exception as e:
-                                print(f"Warning: Could not load metadata for {plugin_id}: {e}")
+                                logger.warning("Could not load metadata for {plugin_id}")
             except Exception as e:  # nosec B110 - metadata pre-load is optional; schema loads fully below
                 logger.debug("Metadata pre-load skipped for plugin %s: %s", plugin_id, e)
         
@@ -406,7 +428,7 @@ def _load_plugin_config_partial(plugin_id):
                 with open(schema_path, 'r', encoding='utf-8') as f:
                     schema = json.load(f)
             except Exception as e:
-                print(f"Warning: Could not load schema for {plugin_id}: {e}")
+                logger.warning("Could not load schema for {plugin_id}")
         
         # Get web UI actions from plugin manifest
         web_ui_actions = []
@@ -417,7 +439,7 @@ def _load_plugin_config_partial(plugin_id):
                     manifest = json.load(f)
                     web_ui_actions = manifest.get('web_ui_actions', [])
             except Exception as e:
-                print(f"Warning: Could not load manifest for {plugin_id}: {e}")
+                logger.warning("Could not load manifest for {plugin_id}")
         
         # Mask secret fields before rendering template (fail closed — never leak secrets)
         schema_properties = schema.get('properties') if isinstance(schema, dict) else None
@@ -453,9 +475,8 @@ def _load_plugin_config_partial(plugin_id):
         )
         
     except Exception as e:
-        import traceback
-        traceback.print_exc()
-        return f'<div class="text-red-500 p-4">Error loading plugin config: {escape(str(e))}</div>', 500
+        logger.error("Error loading plugin config partial for %s", plugin_id, exc_info=True)
+        return '<div class="text-red-500 p-4">Error loading plugin config; see logs for details</div>', 500
 
 
 def _load_starlark_config_partial(app_id):
diff --git a/web_interface/static/v3/js/widgets/base-widget.js b/web_interface/static/v3/js/widgets/base-widget.js
index 18ec5d40..084c8555 100644
--- a/web_interface/static/v3/js/widgets/base-widget.js
+++ b/web_interface/static/v3/js/widgets/base-widget.js
@@ -51,8 +51,10 @@
         sanitizeValue(value) {
             // Base implementation - widgets should override for specific needs
             if (typeof value === 'string') {
-                // Basic XSS prevention
-                return value.replace(/<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi, '');
+                // Strip all HTML tags via the DOM parser to prevent XSS
+                const div = document.createElement('div');
+                div.textContent = value;
+                return div.textContent;
             }
             return value;
         }
diff --git a/web_interface/static/v3/plugins_manager.js b/web_interface/static/v3/plugins_manager.js
index 65bab8ca..c34c45fc 100644
--- a/web_interface/static/v3/plugins_manager.js
+++ b/web_interface/static/v3/plugins_manager.js
@@ -1442,9 +1442,14 @@ function renderInstalledPlugins(plugins) {
         return;
     }
 
-    // Helper function to escape attributes for use in HTML
+    // Helper function to escape values for use in HTML attributes
     const escapeAttr = (text) => {
-        return (text || '').replace(/'/g, "\\'").replace(/"/g, '&quot;');
+        return (text || '')
+            .replace(/&/g, '&amp;')
+            .replace(/"/g, '&quot;')
+            .replace(/'/g, '&#39;')
+            .replace(/</g, '&lt;')
+            .replace(/>/g, '&gt;');
     };
 
     // Helper function to escape for JavaScript strings (use JSON.stringify for proper escaping)
@@ -4507,6 +4512,8 @@ function syncFormToJson() {
     // Deep merge with existing config to preserve nested structures
     function deepMerge(target, source) {
         for (const key in source) {
+            if (key === '__proto__' || key === 'constructor' || key === 'prototype') continue;
+            if (!Object.prototype.hasOwnProperty.call(source, key)) continue;
             if (source[key] && typeof source[key] === 'object' && !Array.isArray(source[key])) {
                 if (!target[key] || typeof target[key] !== 'object' || Array.isArray(target[key])) {
                     target[key] = {};