How can I fix a generic HTTP 5xx error?

In some cases, a web server may display an HTTP 5xx error page (500, 502, etc.) with a generic error message. This error message is generic on purpose – the actual details of the error can be found in the web server’s error log.

The most common cause of an HTTP 5xx error are from lack of available memory or time when PHP is executing – for example, when creating thumbnails from large images, creating many thumbnails, executing a badly coded recursive filter, etc. If you are seeing an HTTP 5xx error message, you must get the error details from the web server’s error log to know what the issue actually is.

Some older versions of PHP are known to have bugs in their ImageMagick library or PHP may have timed-out when trying to create several thumbnail images in a row (see this FAQ for details), or PHP may have run out of memory (see this FAQ for details), or WPSSO Core may be triggering a bug in your theme or another plugin (try disabling WPSSO Core’s use of the WordPress content filter as suggested here).

If an HTTP 5xx error happens in a WordPress edit table:

WPSSO Core, by default, shows an SSO image column in the WordPress post, term and user edit table (see the SSO > Advanced Settings > Columns tab).

If WordPress has not already created the various image sizes required by WPSSO Core (ie. Open Graph, Schema, AMP, etc.) during the image upload process, and you are displaying many rows by default (ie. 20+ items per page selected in the Screen Options tab), and your server is slow to create images (image optimization plugins, for example, are typically very slow), then your web server might time out with an HTTP 502 error in the WordPress edit table.

If you think WordPress might be slow to create images:

  1. If you use an image optimization plugin, try disabling it or using a different (faster) image optimization plugin.
  2. You can also use the WPSSO Tune Image Editors add-on to select the GD image library instead of the default ImageMagick image library. The GD image library is lighter weight and faster than ImageMagick.