diff --git a/first_time_install.sh b/first_time_install.sh
index e43a7b8b..44eed924 100644
--- a/first_time_install.sh
+++ b/first_time_install.sh
@@ -15,8 +15,8 @@ on_error() {
     echo "✗ An error occurred during: $CURRENT_STEP (line $line_no, exit $exit_code)" >&2
     if [ -n "${LOG_FILE:-}" ]; then
         echo "See the log for details: $LOG_FILE" >&2
-        echo "-- Last 50 lines from log --" >&2
-        tail -n 50 "$LOG_FILE" >&2 || true
+        echo "-- Last 100 lines from log --" >&2
+        tail -n 100 "$LOG_FILE" >&2 || true
     fi
     echo "\nCommon fixes:" >&2
     echo "- Ensure the Pi is online (try: ping -c1 8.8.8.8)." >&2
@@ -202,8 +202,33 @@ retry() {
     done
 }
 
-apt_update() { retry apt update; }
-apt_install() { retry apt install -y "$@"; }
+# Wait for another apt/dpkg process (commonly unattended-upgrades running
+# shortly after first boot) to release its lock before we try apt ourselves.
+# Without this, apt_update/apt_install can fail outright in the first couple
+# minutes after a fresh Pi OS boot with a generic "Command failed after 3
+# attempts" error.
+wait_for_apt_lock() {
+    command -v flock >/dev/null 2>&1 || return 0
+    local lock_file="/var/lib/dpkg/lock-frontend"
+    local max_wait=180
+    local waited=0
+    local printed=0
+    while ! flock -n "$lock_file" -c true 2>/dev/null; do
+        if [ "$printed" -eq 0 ]; then
+            echo "⚠ Waiting for another apt/dpkg process to finish (e.g. unattended-upgrades on first boot)..."
+            printed=1
+        fi
+        if [ "$waited" -ge "$max_wait" ]; then
+            echo "⚠ Still waiting after ${max_wait}s; proceeding anyway."
+            break
+        fi
+        sleep 5
+        waited=$((waited+5))
+    done
+}
+
+apt_update() { wait_for_apt_lock; retry apt update; }
+apt_install() { wait_for_apt_lock; retry apt install -y "$@"; }
 apt_remove() { apt-get remove -y "$@" || true; }
 
 check_network() {
@@ -222,6 +247,22 @@ check_network() {
     exit 1
 }
 
+check_disk_space() {
+    command -v df >/dev/null 2>&1 || return 0
+    local available_mb
+    available_mb=$(df -m "$PROJECT_ROOT_DIR" | awk 'NR==2{print $4}')
+    available_mb=${available_mb:-0}
+    if [ "$available_mb" -lt 500 ]; then
+        echo "✗ ERROR: Insufficient disk space: ${available_mb}MB available (need at least 500MB)"
+        echo "  Free up space first, e.g.: sudo apt clean && sudo apt autoremove"
+        exit 1
+    elif [ "$available_mb" -lt 1024 ]; then
+        echo "⚠ Limited disk space: ${available_mb}MB available (recommend at least 1GB for the rpi-rgb-led-matrix build in Step 6)"
+    else
+        echo "✓ Disk space sufficient: ${available_mb}MB available"
+    fi
+}
+
 echo ""
 echo "This script will perform the following steps:"
 echo "1. Install system dependencies"
@@ -271,8 +312,9 @@ CURRENT_STEP="Install system dependencies"
 echo "Step 1: Installing system dependencies..."
 echo "----------------------------------------"
 
-# Ensure network is available before APT operations
+# Pre-flight checks before APT operations
 check_network
+check_disk_space
 
 # Update package list
 apt_update
@@ -822,14 +864,14 @@ else
         # Try to initialize submodule if .gitmodules exists
         if [ -f "$PROJECT_ROOT_DIR/.gitmodules" ] && grep -q "rpi-rgb-led-matrix" "$PROJECT_ROOT_DIR/.gitmodules"; then
             echo "Initializing rpi-rgb-led-matrix submodule..."
-            if ! git submodule update --init --recursive rpi-rgb-led-matrix-master 2>&1; then
+            if ! retry git submodule update --init --recursive rpi-rgb-led-matrix-master; then
                 echo "⚠ Submodule init failed, cloning directly from GitHub..."
-                git clone https://github.com/hzeller/rpi-rgb-led-matrix.git rpi-rgb-led-matrix-master
+                retry git clone https://github.com/hzeller/rpi-rgb-led-matrix.git rpi-rgb-led-matrix-master
             fi
         else
             # Fallback: clone directly if submodule not configured
             echo "Submodule not configured, cloning directly from GitHub..."
-            git clone https://github.com/hzeller/rpi-rgb-led-matrix.git rpi-rgb-led-matrix-master
+            retry git clone https://github.com/hzeller/rpi-rgb-led-matrix.git rpi-rgb-led-matrix-master
         fi
     fi
     
@@ -841,23 +883,34 @@ else
             cd "$PROJECT_ROOT_DIR"
             rm -rf rpi-rgb-led-matrix-master
             if [ -f "$PROJECT_ROOT_DIR/.gitmodules" ] && grep -q "rpi-rgb-led-matrix" "$PROJECT_ROOT_DIR/.gitmodules"; then
-                git submodule update --init --recursive rpi-rgb-led-matrix-master
+                retry git submodule update --init --recursive rpi-rgb-led-matrix-master
             else
-                git clone https://github.com/hzeller/rpi-rgb-led-matrix.git rpi-rgb-led-matrix-master
+                retry git clone https://github.com/hzeller/rpi-rgb-led-matrix.git rpi-rgb-led-matrix-master
             fi
         fi
-        
+
         pushd "$PROJECT_ROOT_DIR/rpi-rgb-led-matrix-master" >/dev/null
         echo "Installing rpi-rgb-led-matrix Python package (scikit-build-core + cmake)..."
         echo "  Build deps required: python-dev-is-python3 cmake"
         echo "  This compiles C++ — may take 2-5 minutes on Pi 4/5..."
-        if ! python3 -m pip install --break-system-packages .; then
+        BUILD_OUTPUT=$(mktemp)
+        BUILD_SUCCESS=false
+        if python3 -m pip install --break-system-packages . > "$BUILD_OUTPUT" 2>&1; then
+            BUILD_SUCCESS=true
+        fi
+        cat "$BUILD_OUTPUT" >> "$LOG_FILE"
+        if [ "$BUILD_SUCCESS" != true ]; then
             echo "✗ Failed to install rpi-rgb-led-matrix Python package"
             echo "  Ensure build tools are installed:"
             echo "  sudo apt install -y python-dev-is-python3 cmake build-essential"
+            echo ""
+            echo "-- Last 50 lines of build output --"
+            tail -n 50 "$BUILD_OUTPUT"
+            rm -f "$BUILD_OUTPUT"
             popd >/dev/null
             exit 1
         fi
+        rm -f "$BUILD_OUTPUT"
         popd >/dev/null
     else
         echo "✗ rpi-rgb-led-matrix-master directory not found at $PROJECT_ROOT_DIR"
@@ -912,7 +965,9 @@ else
     # Try to install dependencies using the smart installer if available
     if [ -f "$PROJECT_ROOT_DIR/scripts/install_dependencies_apt.py" ]; then
         echo "Using smart dependency installer..."
-        python3 "$PROJECT_ROOT_DIR/scripts/install_dependencies_apt.py"
+        # -u: unbuffered stdout/stderr so output is captured in $LOG_FILE in
+        # real time and in order relative to this script's own echo statements
+        python3 -u "$PROJECT_ROOT_DIR/scripts/install_dependencies_apt.py"
     else
         echo "Using pip to install dependencies..."
         if [ -f "$PROJECT_ROOT_DIR/requirements_web_v2.txt" ]; then
diff --git a/scripts/install/one-shot-install.sh b/scripts/install/one-shot-install.sh
index ddac1115..472b687f 100755
--- a/scripts/install/one-shot-install.sh
+++ b/scripts/install/one-shot-install.sh
@@ -340,9 +340,14 @@ main() {
     echo ""
     
     # Execute with proper error handling and non-interactive mode
-    # Temporarily disable errexit to capture exit code instead of exiting immediately
+    # Temporarily disable errexit AND the ERR trap to capture exit code instead of
+    # exiting immediately. `set +e` alone does not suppress the ERR trap, so without
+    # `trap '' ERR` a non-zero exit from first_time_install.sh would trigger on_error
+    # here with the generic "Main installation" message instead of the detailed
+    # if/else handling below.
     set +e
-    
+    trap '' ERR
+
     # Check /tmp permissions - only fix if actually wrong (common in automated scenarios)
     # When running manually, /tmp usually has correct permissions (1777)
     TMP_PERMS=$(stat -c '%a' /tmp 2>/dev/null || echo "unknown")
@@ -370,6 +375,7 @@ main() {
         sudo -E env TMPDIR=/tmp LEDMATRIX_ASSUME_YES=1 bash ./first_time_install.sh -y </dev/null
     fi
     INSTALL_EXIT_CODE=$?
+    trap 'on_error $LINENO' ERR  # Re-enable ERR trap
     set -e  # Re-enable errexit
     
     if [ $INSTALL_EXIT_CODE -eq 0 ]; then
diff --git a/scripts/install_dependencies_apt.py b/scripts/install_dependencies_apt.py
index ef019118..a12d0b30 100644
--- a/scripts/install_dependencies_apt.py
+++ b/scripts/install_dependencies_apt.py
@@ -6,46 +6,67 @@ then falls back to pip with --break-system-packages
 
 import subprocess
 import sys
+import tempfile
 import warnings
+from collections import deque
 from pathlib import Path
 
+# How many trailing lines of a failed command's output to keep for the
+# end-of-run failure summary. Keeps the root cause near the end of the log,
+# which is where first_time_install.sh's error handler tails from.
+ERROR_TAIL_LINES = 15
+
+
+def _run(cmd):
+    """Run a command, streaming combined stdout/stderr to a temp file.
+
+    Returns (success, output) instead of raising, so callers can report
+    *why* a command failed rather than just that it failed. `output` is
+    bounded to the last ERROR_TAIL_LINES lines so failures from very
+    chatty commands (e.g. pip build logs) don't get buffered in memory.
+    """
+    with tempfile.TemporaryFile(mode='w+b') as f:
+        result = subprocess.run(cmd, stdout=f, stderr=subprocess.STDOUT)  # nosec B603 B607 - hardcoded apt/pip args  # nosemgrep
+        f.seek(0)
+        # Stream line-by-line so only the last ERROR_TAIL_LINES are ever held
+        # in memory, regardless of how much output the command produced.
+        tail = deque(
+            (line.decode('utf-8', errors='replace').rstrip('\n') for line in f),
+            maxlen=ERROR_TAIL_LINES,
+        )
+    return result.returncode == 0, '\n'.join(tail)
+
+
 def install_via_apt(package_name):
-    """Try to install a package via apt."""
-    try:
-        # Map pip package names to apt package names
-        apt_package_map = {
-            'flask': 'python3-flask',
-            'PIL': 'python3-pil',
-            'freetype': 'python3-freetype',
-            'psutil': 'python3-psutil',
-            'werkzeug': 'python3-werkzeug',
-            'numpy': 'python3-numpy',
-            'requests': 'python3-requests',
-            'python-dateutil': 'python3-dateutil',
-            'pytz': 'python3-tz',
-            'geopy': 'python3-geopy',
-            'unidecode': 'python3-unidecode',
-            'websockets': 'python3-websockets',
-            'websocket-client': 'python3-websocket-client'
-        }
-        
-        apt_package = apt_package_map.get(package_name, f'python3-{package_name}')
-        
-        print(f"Trying to install {apt_package} via apt...")
-        subprocess.check_call([
-            'sudo', 'apt', 'update'
-        ], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-        
-        subprocess.check_call([
-            'sudo', 'apt', 'install', '-y', apt_package
-        ], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-        
+    """Try to install a package via apt. Returns (success, output)."""
+    # Map pip package names to apt package names
+    apt_package_map = {
+        'flask': 'python3-flask',
+        'PIL': 'python3-pil',
+        'freetype': 'python3-freetype',
+        'psutil': 'python3-psutil',
+        'werkzeug': 'python3-werkzeug',
+        'numpy': 'python3-numpy',
+        'requests': 'python3-requests',
+        'python-dateutil': 'python3-dateutil',
+        'pytz': 'python3-tz',
+        'geopy': 'python3-geopy',
+        'unidecode': 'python3-unidecode',
+        'websockets': 'python3-websockets',
+        'websocket-client': 'python3-websocket-client'
+    }
+
+    apt_package = apt_package_map.get(package_name, f'python3-{package_name}')
+
+    print(f"Trying to install {apt_package} via apt...")
+    success, output = _run(['sudo', 'apt', 'install', '-y', apt_package])
+    if success:
         print(f"Successfully installed {apt_package} via apt")
-        return True
-        
-    except subprocess.CalledProcessError:
-        print(f"Failed to install {package_name} via apt, will try pip")
-        return False
+        return True, ""
+
+    print(f"Failed to install {apt_package} via apt, will try pip")
+    return False, output
+
 
 def install_via_pip(package_name):
     """Install a package via pip with --break-system-packages and --prefer-binary.
@@ -54,34 +75,65 @@ def install_via_pip(package_name):
     Debian/Ubuntu-based systems without a virtual environment.
     --prefer-binary prefers pre-built wheels over source distributions to avoid
     exhausting /tmp space during compilation.
+
+    Returns (success, output).
     """
-    try:
-        print(f"Installing {package_name} via pip...")
-        subprocess.check_call([
-            sys.executable, '-m', 'pip', 'install', '--break-system-packages', '--prefer-binary', package_name
-        ])
+    print(f"Installing {package_name} via pip...")
+    success, output = _run([
+        sys.executable, '-m', 'pip', 'install', '--break-system-packages', '--prefer-binary', package_name
+    ])
+    if success:
         print(f"Successfully installed {package_name} via pip")
-        return True
-    except subprocess.CalledProcessError as e:
-        print(f"Failed to install {package_name} via pip: {e}")
-        return False
+        return True, ""
+
+    print(f"Failed to install {package_name} via pip (see failure summary at end of log)")
+    return False, output
+
+
+# Distribution (pip/apt) names whose importable module name differs.
+IMPORT_NAME_MAP = {
+    'python-dateutil': 'dateutil',
+    'websocket-client': 'websocket',
+}
+
 
 def check_package_installed(package_name):
     """Check if a package is already installed."""
+    import_name = IMPORT_NAME_MAP.get(package_name, package_name)
     # Suppress deprecation warnings when checking if packages are installed
     # (we're just checking, not using them)
     with warnings.catch_warnings():
         warnings.filterwarnings('ignore', category=DeprecationWarning)
         try:
-            __import__(package_name)
+            __import__(import_name)
             return True
         except ImportError:
             return False
 
+
+def print_failure_summary(failed_packages, failure_details):
+    print("\n" + "=" * 60)
+    print("DEPENDENCY INSTALLATION FAILURES - DETAILS")
+    print("=" * 60)
+    for package in failed_packages:
+        print(f"\nPackage: {package}")
+        print("-" * 40)
+        output = failure_details.get(package, "").strip()
+        if not output:
+            print("  (no output captured)")
+            continue
+        for line in output.splitlines()[-ERROR_TAIL_LINES:]:
+            print(f"  {line}")
+    print("=" * 60)
+
+
 def main():
     """Main installation function."""
     print("Installing dependencies for LED Matrix Web Interface V2...")
-    
+
+    print("Refreshing apt package index...")
+    _run(['sudo', 'apt', 'update'])  # best-effort; individual installs surface their own errors
+
     # List of required packages
     required_packages = [
         'flask',
@@ -98,19 +150,23 @@ def main():
         'websockets',
         'websocket-client'
     ]
-    
+
     failed_packages = []
-    
+    failure_details = {}
+
     for package in required_packages:
         if check_package_installed(package):
             print(f"{package} is already installed")
             continue
-            
+
         # Try apt first, then pip
-        if not install_via_apt(package):
-            if not install_via_pip(package):
+        ok, apt_output = install_via_apt(package)
+        if not ok:
+            ok, pip_output = install_via_pip(package)
+            if not ok:
                 failed_packages.append(package)
-    
+                failure_details[package] = pip_output or apt_output
+
     # Install packages that don't have apt equivalents
     special_packages = [
         'timezonefinder>=6.5.0,<7.0.0',
@@ -122,47 +178,49 @@ def main():
         'python-socketio>=5.11.0,<6.0.0',
         'python-engineio>=4.9.0,<5.0.0'
     ]
-    
+
     for package in special_packages:
-        if not install_via_pip(package):
+        ok, pip_output = install_via_pip(package)
+        if not ok:
             failed_packages.append(package)
-    
+            failure_details[package] = pip_output
+
     # Install rgbmatrix module from local source (optional - may already be installed in Step 6)
     # Check if already installed first
     if check_package_installed('rgbmatrix'):
         print("rgbmatrix module already installed, skipping...")
     else:
         print("Installing rgbmatrix module from local source...")
-        try:
-            # Get project root (parent of scripts directory)
-            PROJECT_ROOT = Path(__file__).parent.parent
-            rgbmatrix_path = PROJECT_ROOT / 'rpi-rgb-led-matrix-master' / 'bindings' / 'python'
-            if rgbmatrix_path.exists():
-                # Check if the module has been built (look for setup.py)
-                setup_py = rgbmatrix_path / 'setup.py'
-                if setup_py.exists():
-                    # Try installing - use regular install, not editable mode
-                    # This is optional for web interface and should already be installed in Step 6
-                    subprocess.check_call([
-                        sys.executable, '-m', 'pip', 'install', '--break-system-packages', str(rgbmatrix_path)
-                    ], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+        # Get project root (parent of scripts directory)
+        PROJECT_ROOT = Path(__file__).parent.parent
+        rgbmatrix_path = PROJECT_ROOT / 'rpi-rgb-led-matrix-master' / 'bindings' / 'python'
+        if rgbmatrix_path.exists():
+            # Check if the module has been built (look for setup.py)
+            setup_py = rgbmatrix_path / 'setup.py'
+            if setup_py.exists():
+                # Try installing - use regular install, not editable mode
+                # This is optional for web interface and should already be installed in Step 6
+                ok, output = _run([sys.executable, '-m', 'pip', 'install', '--break-system-packages', str(rgbmatrix_path)])
+                if ok:
                     print("rgbmatrix module installed successfully")
                 else:
-                    print("Warning: rgbmatrix setup.py not found, module may need to be built first")
-                    print("  This is normal if Step 6 hasn't completed yet.")
+                    # Don't fail the whole installation - rgbmatrix is optional for web interface
+                    # and should be installed in Step 6 of first_time_install.sh
+                    print("Warning: Failed to install rgbmatrix module:")
+                    for line in output.strip().splitlines()[-ERROR_TAIL_LINES:]:
+                        print(f"  {line}")
+                    print("  This is normal if rgbmatrix hasn't been built yet (Step 6).")
+                    print("  The web interface will work without it.")
             else:
-                print("Warning: rgbmatrix source not found (this is normal if Step 6 hasn't run yet)")
-        except subprocess.CalledProcessError as e:
-            # Don't fail the whole installation - rgbmatrix is optional for web interface
-            # and should be installed in Step 6 of first_time_install.sh
-            print(f"Warning: Failed to install rgbmatrix module: {e}")
-            print("  This is normal if rgbmatrix hasn't been built yet (Step 6).")
-            print("  The web interface will work without it.")
-            # Don't add to failed_packages since it's optional
-    
+                print("Warning: rgbmatrix setup.py not found, module may need to be built first")
+                print("  This is normal if Step 6 hasn't completed yet.")
+        else:
+            print("Warning: rgbmatrix source not found (this is normal if Step 6 hasn't run yet)")
+
     if failed_packages:
         print(f"\nFailed to install the following packages: {failed_packages}")
         print("You may need to install them manually or check your system configuration.")
+        print_failure_summary(failed_packages, failure_details)
         return False
     else:
         print("\nAll dependencies installed successfully!")