A Drupal module to help track down HTTP 4XX client errors.

• Plug

Enable the module, being sure to let Composer Manager update libraries if required. Browse to Admin / Reports / Client Error Trace, and use the form to run tests on any problematic URLs.

• Access Content: Checks that users have the access content permission on node URLs.

This module uses a backport of the Drupal 8 plugin system to let other modules add traces for debugging client errors. For example, many sites have custom CDN or caching configurations. By writing a custom module with plugins for each system to check, it is possible for Client Error Trace to provide detailed reports.

• Drupal 8 Plugins Explained.
• The "Access Content" plugin included with this module is a good starting point to learn how to add your own plugins to your own custom modules.
• plug_example is also an excellent guide to the Drupal 8 plugin system.

1. In your module, create a src/Plugin/client_error directory.
2. Create a new class in that directory that extends ClientErrorBase and implements ClientErrorInterface.
3. Annotate the class with the @ClientError annotation containing:
   • An id property, with the name of your plugin in underscore format.
   • A plain-text description property describing your plugin.
   • An integer status_code property describing what HTTP error code your plugin assists in debugging. This will generally be 403 or 404.
4. Create a new class that extends ReportBase and implements ReportInterface to use for reporting the results of your client error plugin. Return a new instance of this class from your execute() method.
5. Clear all caches.
6. Browse to admin/reports/client-error, and your new plugin should be listed.