Drupal-Debug-Hints.md

@@ -14,6 +14,18 @@ $config["system.logging"]["error_level"] = "verbose";
 
 Might have to ignore the readonly flag (with `:w!`).
 
+# Disable APCu extension for classloading
+
+When classes are not found, even though they are definitely there:
+
+Run `vim web/sites/default/settings.php` and add:
+
+```php
+$settings['class_loader_auto_detect'] = FALSE;
+```
+
+Might have to ignore the readonly flag (with `:w!`).
+
 # Manually deleting log messages
 
 Sometimes the log page fails to load with a fatal error.