diff --git a/plugins/mqtt-notifications b/plugins/mqtt-notifications
index 3bd955a3..5c23a842 160000
--- a/plugins/mqtt-notifications
+++ b/plugins/mqtt-notifications
@@ -1 +1 @@
-Subproject commit 3bd955a329a9e07933f34098bf26a1f1e0e0c31e
+Subproject commit 5c23a842d8efc6e1253bc3dfc67c65ce37a193cc
diff --git a/scripts/add_defaults_to_schemas.py b/scripts/add_defaults_to_schemas.py
new file mode 100755
index 00000000..9460c9ca
--- /dev/null
+++ b/scripts/add_defaults_to_schemas.py
@@ -0,0 +1,231 @@
+#!/usr/bin/env python3
+"""
+Script to add default values to plugin config schemas where missing.
+
+This ensures that configs never start with None values, improving user experience
+and preventing validation errors.
+"""
+
+import json
+import sys
+from pathlib import Path
+from typing import Any, Dict, List, Optional
+
+
+def get_default_for_field(prop: Dict[str, Any]) -> Any:
+    """
+    Determine a sensible default value for a field based on its type and constraints.
+    
+    Args:
+        prop: Field property schema
+        
+    Returns:
+        Default value or None if no default should be added
+    """
+    prop_type = prop.get('type')
+    
+    # Handle union types (array with multiple types)
+    if isinstance(prop_type, list):
+        # Use the first non-null type
+        prop_type = next((t for t in prop_type if t != 'null'), prop_type[0] if prop_type else 'string')
+    
+    if prop_type == 'boolean':
+        return False
+    
+    elif prop_type == 'number':
+        # For numbers, use minimum if available, or a sensible default
+        minimum = prop.get('minimum')
+        maximum = prop.get('maximum')
+        
+        if minimum is not None:
+            return minimum
+        elif maximum is not None:
+            # Use a reasonable fraction of max (like 30% or minimum 1)
+            return max(1, int(maximum * 0.3))
+        else:
+            # No constraints, use 0
+            return 0
+    
+    elif prop_type == 'integer':
+        # Similar to number
+        minimum = prop.get('minimum')
+        maximum = prop.get('maximum')
+        
+        if minimum is not None:
+            return minimum
+        elif maximum is not None:
+            return max(1, int(maximum * 0.3))
+        else:
+            return 0
+    
+    elif prop_type == 'string':
+        # Only add default for strings if it makes sense
+        # Check if there's an enum - use first value
+        enum_values = prop.get('enum')
+        if enum_values:
+            return enum_values[0]
+        
+        # For optional string fields, empty string might be okay, but be cautious
+        # We'll skip adding defaults for strings unless explicitly needed
+        return None
+    
+    elif prop_type == 'array':
+        # Empty array as default
+        return []
+    
+    elif prop_type == 'object':
+        # Empty object - but we'll handle nested objects separately
+        return {}
+    
+    return None
+
+
+def should_add_default(prop: Dict[str, Any], field_path: str) -> bool:
+    """
+    Determine if we should add a default value to this field.
+    
+    Args:
+        prop: Field property schema
+        field_path: Dot-separated path to the field
+        
+    Returns:
+        True if default should be added
+    """
+    # Skip if already has a default
+    if 'default' in prop:
+        return False
+    
+    # Skip secret fields (they should be user-provided)
+    if prop.get('x-secret', False):
+        return False
+    
+    # Skip API keys and similar sensitive fields
+    field_name = field_path.split('.')[-1].lower()
+    sensitive_keywords = ['key', 'password', 'secret', 'token', 'auth', 'credential']
+    if any(keyword in field_name for keyword in sensitive_keywords):
+        return False
+    
+    prop_type = prop.get('type')
+    if isinstance(prop_type, list):
+        prop_type = next((t for t in prop_type if t != 'null'), prop_type[0] if prop_type else None)
+    
+    # Only add defaults for certain types
+    if prop_type in ('boolean', 'number', 'integer', 'array'):
+        return True
+    
+    # For strings, only if there's an enum
+    if prop_type == 'string' and 'enum' in prop:
+        return True
+    
+    return False
+
+
+def add_defaults_recursive(schema: Dict[str, Any], path: str = "", modified: List[str] = None) -> bool:
+    """
+    Recursively add default values to schema fields.
+    
+    Args:
+        schema: Schema dictionary to modify
+        path: Current path in the schema (for logging)
+        modified: List to track which fields were modified
+        
+    Returns:
+        True if any modifications were made
+    """
+    if modified is None:
+        modified = []
+    
+    if not isinstance(schema, dict) or 'properties' not in schema:
+        return False
+    
+    changes_made = False
+    
+    for key, prop in schema['properties'].items():
+        if not isinstance(prop, dict):
+            continue
+        
+        current_path = f"{path}.{key}" if path else key
+        
+        # Check nested objects
+        if prop.get('type') == 'object' and 'properties' in prop:
+            if add_defaults_recursive(prop, current_path, modified):
+                changes_made = True
+        
+        # Add default if appropriate
+        if should_add_default(prop, current_path):
+            default_value = get_default_for_field(prop)
+            if default_value is not None:
+                prop['default'] = default_value
+                modified.append(current_path)
+                changes_made = True
+                print(f"  Added default to {current_path}: {default_value} (type: {prop.get('type')})")
+    
+    return changes_made
+
+
+def process_schema_file(schema_path: Path) -> bool:
+    """
+    Process a single schema file to add defaults.
+    
+    Args:
+        schema_path: Path to the schema file
+        
+    Returns:
+        True if file was modified
+    """
+    print(f"\nProcessing: {schema_path}")
+    
+    try:
+        with open(schema_path, 'r', encoding='utf-8') as f:
+            schema = json.load(f)
+    except Exception as e:
+        print(f"  Error reading schema: {e}")
+        return False
+    
+    modified_fields = []
+    changes_made = add_defaults_recursive(schema, modified=modified_fields)
+    
+    if changes_made:
+        # Write back with pretty formatting
+        with open(schema_path, 'w', encoding='utf-8') as f:
+            json.dump(schema, f, indent=2, ensure_ascii=False)
+            f.write('\n')  # Add trailing newline
+        
+        print(f"  ✓ Modified {len(modified_fields)} fields")
+        return True
+    else:
+        print(f"  ✓ No changes needed")
+        return False
+
+
+def main():
+    """Main entry point."""
+    project_root = Path(__file__).parent.parent
+    plugins_dir = project_root / 'plugins'
+    
+    if not plugins_dir.exists():
+        print(f"Error: Plugins directory not found: {plugins_dir}")
+        sys.exit(1)
+    
+    # Find all config_schema.json files
+    schema_files = list(plugins_dir.rglob('config_schema.json'))
+    
+    if not schema_files:
+        print("No config_schema.json files found")
+        sys.exit(0)
+    
+    print(f"Found {len(schema_files)} schema files")
+    
+    modified_count = 0
+    for schema_file in sorted(schema_files):
+        if process_schema_file(schema_file):
+            modified_count += 1
+    
+    print(f"\n{'='*60}")
+    print(f"Summary: Modified {modified_count} out of {len(schema_files)} schema files")
+    print(f"{'='*60}")
+
+
+if __name__ == '__main__':
+    main()
+
diff --git a/src/plugin_system/schema_manager.py b/src/plugin_system/schema_manager.py
index 72d701d8..9cd9fd2d 100644
--- a/src/plugin_system/schema_manager.py
+++ b/src/plugin_system/schema_manager.py
@@ -394,24 +394,54 @@ class SchemaManager:
     def merge_with_defaults(self, config: Dict[str, Any], defaults: Dict[str, Any]) -> Dict[str, Any]:
         """
         Merge configuration with defaults, preserving user values.
+        Also replaces None values with defaults to ensure config never has None from the start.
         
         Args:
             config: User configuration
             defaults: Default values from schema
             
         Returns:
-            Merged configuration with defaults applied where missing
+            Merged configuration with defaults applied where missing or None
         """
-        merged = defaults.copy()
+        merged = copy.deepcopy(defaults)
         
-        def deep_merge(target: Dict[str, Any], source: Dict[str, Any]) -> None:
-            """Recursively merge source into target."""
+        def deep_merge(target: Dict[str, Any], source: Dict[str, Any], default_dict: Dict[str, Any]) -> None:
+            """Recursively merge source into target, replacing None with defaults."""
             for key, value in source.items():
+                default_value = default_dict.get(key)
+                
                 if key in target and isinstance(target[key], dict) and isinstance(value, dict):
-                    deep_merge(target[key], value)
+                    # Both are dicts, recursively merge
+                    if isinstance(default_value, dict):
+                        deep_merge(target[key], value, default_value)
+                    else:
+                        deep_merge(target[key], value, {})
+                elif value is None and default_value is not None:
+                    # Value is None and we have a default, use the default
+                    target[key] = copy.deepcopy(default_value) if isinstance(default_value, (dict, list)) else default_value
                 else:
-                    target[key] = value
+                    # Normal merge: user value takes precedence (copy if dict/list)
+                    if isinstance(value, (dict, list)):
+                        target[key] = copy.deepcopy(value)
+                    else:
+                        target[key] = value
         
-        deep_merge(merged, config)
+        deep_merge(merged, config, defaults)
+        
+        # Final pass: replace any remaining None values at any level with defaults
+        def replace_none_with_defaults(target: Dict[str, Any], default_dict: Dict[str, Any]) -> None:
+            """Recursively replace None values with defaults."""
+            for key in list(target.keys()):
+                value = target[key]
+                default_value = default_dict.get(key)
+                
+                if value is None and default_value is not None:
+                    # Replace None with default
+                    target[key] = copy.deepcopy(default_value) if isinstance(default_value, (dict, list)) else default_value
+                elif isinstance(value, dict) and isinstance(default_value, dict):
+                    # Recursively process nested dicts
+                    replace_none_with_defaults(value, default_value)
+        
+        replace_none_with_defaults(merged, defaults)
         return merged
 
diff --git a/web_interface/blueprints/api_v3.py b/web_interface/blueprints/api_v3.py
index 5aa32e1b..fdf180d9 100644
--- a/web_interface/blueprints/api_v3.py
+++ b/web_interface/blueprints/api_v3.py
@@ -2914,6 +2914,43 @@ def _get_schema_property(schema, key_path):
     return None
 
 
+def _is_field_required(key_path, schema):
+    """
+    Check if a field is required according to the schema.
+    
+    Args:
+        key_path: Dot-separated path like "mqtt.username"
+        schema: The JSON schema dict
+    
+    Returns:
+        True if field is required, False otherwise
+    """
+    if not schema or 'properties' not in schema:
+        return False
+    
+    parts = key_path.split('.')
+    if len(parts) == 1:
+        # Top-level field
+        required = schema.get('required', [])
+        return parts[0] in required
+    else:
+        # Nested field - navigate to parent object
+        parent_path = '.'.join(parts[:-1])
+        field_name = parts[-1]
+        
+        # Get parent property
+        parent_prop = _get_schema_property(schema, parent_path)
+        if not parent_prop or 'properties' not in parent_prop:
+            return False
+        
+        # Check if field is required in parent
+        required = parent_prop.get('required', [])
+        return field_name in required
+
+
+# Sentinel object to indicate a field should be skipped (not set in config)
+_SKIP_FIELD = object()
+
 def _parse_form_value_with_schema(value, key_path, schema):
     """
     Parse a form value using schema information to determine correct type.
@@ -2925,7 +2962,7 @@ def _parse_form_value_with_schema(value, key_path, schema):
         schema: The plugin's JSON schema
     
     Returns:
-        Parsed value with correct type
+        Parsed value with correct type, or _SKIP_FIELD to indicate the field should not be set
     """
     import json
     
@@ -2940,6 +2977,22 @@ def _parse_form_value_with_schema(value, key_path, schema):
         # If schema says it's an object, return empty dict instead of None
         if prop and prop.get('type') == 'object':
             return {}
+        # If it's an optional string field, preserve empty string instead of None
+        if prop and prop.get('type') == 'string':
+            if not _is_field_required(key_path, schema):
+                return ""  # Return empty string for optional string fields
+        # For number/integer fields, check if they have defaults or are required
+        if prop:
+            prop_type = prop.get('type')
+            if prop_type in ('number', 'integer'):
+                # If field has a default, use it
+                if 'default' in prop:
+                    return prop['default']
+                # If field is not required and has no default, skip setting it
+                if not _is_field_required(key_path, schema):
+                    return _SKIP_FIELD
+                # If field is required but empty, return None (validation will fail, which is correct)
+                return None
         return None
     
     # Handle string values
@@ -3029,8 +3082,12 @@ def _set_nested_value(config, key_path, value):
     Args:
         config: The config dict to modify
         key_path: Dot-separated path (e.g., "customization.period_text.font")
-        value: The value to set
+        value: The value to set (or _SKIP_FIELD to skip setting)
     """
+    # Skip setting if value is the sentinel
+    if value is _SKIP_FIELD:
+        return
+    
     parts = key_path.split('.')
     current = config
     
@@ -3231,7 +3288,9 @@ def save_plugin_config():
                 import logging
                 logger = logging.getLogger(__name__)
                 logger.debug(f"Combined indexed array field {base_path}: {values} -> {combined_value} -> {parsed_value}")
-                _set_nested_value(plugin_config, base_path, parsed_value)
+                # Only set if not skipped
+                if parsed_value is not _SKIP_FIELD:
+                    _set_nested_value(plugin_config, base_path, parsed_value)
             
             # Process remaining (non-indexed) fields
             # Skip any base paths that were processed as indexed arrays
@@ -3249,8 +3308,9 @@ def save_plugin_config():
                                 import logging
                                 logger = logging.getLogger(__name__)
                                 logger.debug(f"Array field {key}: form value='{value}' -> parsed={parsed_value}")
-                        # Use helper to set nested values correctly
-                        _set_nested_value(plugin_config, key, parsed_value)
+                        # Use helper to set nested values correctly (skips if _SKIP_FIELD)
+                        if parsed_value is not _SKIP_FIELD:
+                            _set_nested_value(plugin_config, key, parsed_value)
             
             # Post-process: Fix array fields that might have been incorrectly structured
             # This handles cases where array fields are stored as dicts (e.g., from indexed form fields)
diff --git a/web_interface/templates/v3/base.html b/web_interface/templates/v3/base.html
index 8cc9c7c6..03a3fa78 100644
--- a/web_interface/templates/v3/base.html
+++ b/web_interface/templates/v3/base.html
@@ -4209,13 +4209,28 @@
                 const btn = event.target.querySelector('[type=submit]');
                 if (btn) btn.disabled = false;
                 
-                if (event.detail.successful) {
-                    showNotification('Configuration saved successfully!', 'success');
+                const xhr = event.detail.xhr;
+                const status = xhr?.status || 0;
+                
+                // Check if request was successful (2xx status codes)
+                if (status >= 200 && status < 300) {
+                    // Try to get message from response JSON
+                    let message = 'Configuration saved successfully!';
+                    try {
+                        if (xhr?.responseJSON?.message) {
+                            message = xhr.responseJSON.message;
+                        } else if (xhr?.responseText) {
+                            const responseData = JSON.parse(xhr.responseText);
+                            message = responseData.message || message;
+                        }
+                    } catch (e) {
+                        // Use default message if parsing fails
+                    }
+                    showNotification(message, 'success');
                 } else {
-                    // Log detailed error information
-                    const xhr = event.detail.xhr;
+                    // Request failed - log detailed error information
                     console.error('Config save failed:', {
-                        status: xhr?.status,
+                        status: status,
                         statusText: xhr?.statusText,
                         responseText: xhr?.responseText
                     });
@@ -4223,7 +4238,13 @@
                     // Try to parse error response
                     let errorMessage = 'Failed to save configuration';
                     try {
-                        if (xhr?.responseText) {
+                        if (xhr?.responseJSON) {
+                            const errorData = xhr.responseJSON;
+                            errorMessage = errorData.message || errorData.details || errorMessage;
+                            if (errorData.validation_errors) {
+                                errorMessage += ': ' + errorData.validation_errors.join(', ');
+                            }
+                        } else if (xhr?.responseText) {
                             const errorData = JSON.parse(xhr.responseText);
                             errorMessage = errorData.message || errorData.details || errorMessage;
                             if (errorData.validation_errors) {
@@ -4241,7 +4262,10 @@
             
             // Handle toggle response
             window.handleToggleResponse = function(event, pluginId) {
-                if (event.detail.successful) {
+                const xhr = event.detail.xhr;
+                const status = xhr?.status || 0;
+                
+                if (status >= 200 && status < 300) {
                     // Update UI in place instead of refreshing to avoid duplication
                     const checkbox = document.getElementById(`plugin-enabled-${pluginId}`);
                     const label = checkbox?.nextElementSibling;
@@ -4252,14 +4276,39 @@
                         label.className = `ml-2 text-sm ${isEnabled ? 'text-green-600' : 'text-gray-500'}`;
                     }
                     
-                    showNotification('Plugin status updated', 'success');
+                    // Try to get message from response
+                    let message = 'Plugin status updated';
+                    try {
+                        if (xhr?.responseJSON?.message) {
+                            message = xhr.responseJSON.message;
+                        } else if (xhr?.responseText) {
+                            const responseData = JSON.parse(xhr.responseText);
+                            message = responseData.message || message;
+                        }
+                    } catch (e) {
+                        // Use default message
+                    }
+                    showNotification(message, 'success');
                 } else {
                     // Revert checkbox state on error
                     const checkbox = document.getElementById(`plugin-enabled-${pluginId}`);
                     if (checkbox) {
                         checkbox.checked = !checkbox.checked;
                     }
-                    showNotification('Failed to update plugin status', 'error');
+                    
+                    // Try to get error message from response
+                    let errorMessage = 'Failed to update plugin status';
+                    try {
+                        if (xhr?.responseJSON?.message) {
+                            errorMessage = xhr.responseJSON.message;
+                        } else if (xhr?.responseText) {
+                            const errorData = JSON.parse(xhr.responseText);
+                            errorMessage = errorData.message || errorData.details || errorMessage;
+                        }
+                    } catch (e) {
+                        // Use default message
+                    }
+                    showNotification(errorMessage, 'error');
                 }
             };