Image 404 Fallback

The Image 404 Fallback module automatically replaces 404 (not found) image requests with a configurable fallback image, improving user experience and preventing broken image displays. It intelligently handles both direct file requests and image style derivative requests, ensuring consistent results across your site.

Features

• Automatically detects 404 image requests (including image style derivatives)
• Serves a configurable fallback image
• Supports multiple image formats (JPG, PNG, GIF, WebP, SVG, BMP, ICO, AVIF)
• Includes default fallback images (SVG and PNG)
• Configurable fallback path via admin interface
• Image style aware: Applies requested image styles to fallback images for derivative requests, ensuring correct dimensions and effects
• Handles both direct file requests and image style derivative requests
• Proper HTTP headers and browser caching (200 status code instead of 404)
• Security-aware: Respects Drupal's image style security tokens
• Graceful fallback for image processing failures

How It Works

The module uses Symfony event subscribers to intercept HTTP requests for missing images:

• Catches 404 exceptions for direct image file requests
• Detects and applies image styles to fallback images for derivative requests (e.g., /styles/thumbnail/public/missing.jpg)
• Serves styled fallbacks with correct dimensions and effects when using raster formats (PNG, JPG, GIF, etc.)
• Gracefully handles SVG and other non-processable formats by serving the raw fallback
• Respects Drupal's access control and security protocols

Post-Installation

1. Navigate to Configuration > Media > Image 404 Fallback Settings (/admin/config/media/image-404-fallback)
2. Optionally specify a custom fallback image path:
   • Enter an absolute path (e.g., /var/www/html/sites/default/files/my-fallback.png)
   • Or a path relative to the Drupal root (e.g., sites/default/files/fallback.png)
   • For styled fallbacks, use raster formats (PNG, JPG, GIF, WebP) rather than SVG
3. If left empty, the module will use its default fallback image located at images/placeholder.svg

Requirements

• Drupal 10.x or 11.x
• PHP 8.1 or higher