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WP Hook Debugger

Displays debug details about invalid WordPress hooks

by Philipp Stracker (divimode.com) · github.com/stracker-phil/wp-hook-debugger

★ 0stars

Install

Download source zip No release zip yet

This is the repository archive. It installs, but the folder name will carry the branch suffix and updates will not flow.

Install straight from GitHub with WP-CLI:

wp plugin install https://github.com/stracker-phil/wp-hook-debugger/archive/refs/heads/master.zip
No built-in updater. New versions won't appear under Dashboard → Updates. Install new releases yourself, or let Git Updater track the repository.
Readme github.com/stracker-phil/wp-hook-debugger ↗

This is a small debugging plugin that aids in solving the following PHP warning:

Warning: call_user_func_array() expects parameter 1 to be
a valid callback, first array member is not a valid class
name or object in /wp-includes/class-wp-hook.php on line 287

This warning is triggered, when a plugin or theme tries to hook into a WordPress action or filter but does not provide a valid callback function. It can be difficult to debug this issue, because the warning only tells us, that a hook is invalid, but not which hook causes the problem.

After activating this plugin, you will see a list of all WordPress hooks, that have an invalid callback function. This list will also include valid hooks, but it helps you to track down the problematic plugin/hook.

How to install it

  1. Click on the green ↓ Code button above. Choose "Download ZIP" from the menu
  2. In WordPress: Open the page wp-admin | Plugins | Add New and upload the zip file

Download the plugins zip file:

Download ZIP

How to use it

  1. Install and activate the plugin.
  2. Disable all other plugins.
  3. Load the page that displayed the warning. Scroll to the bottom and look at the "Invalid hooks" section.
  4. Activate each plugin individually and check, if the warning appears.
  5. When the warning appears: Scroll to the bottom again and look at the "Invalid hooks" section. It will show additional items → those additional hooks are causing problems!

Screenshots

While active, the plugin displays inline information on the plugins page:

Activated plugin

Sample of the debug output generated by the plugin:

Sample output