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Guide to Testing Custom Code - Standardized Hooks


This guide explains the basics of how to test Standardized Hook code.

This document lists appropriate test steps for most custom code, and helpful information to troubleshoot common problems. Make certain that you evaluate the testing requirements of your own code, and allow its functionality to determine the appropriate steps.


cPanel Technical Support cannot always assist third-party developers with problems that relate to custom code. For this reason, always test your projects thoroughly before you attempt to use them on production servers.


We strongly recommend that you use the Cpanel::Logger module to log messages to the /usr/local/cpanel/logs/error_log file. Some of the steps in this document require that your code logs messages.

Testing steps

Enable Debug Mode on your development server

When you test Standardized Hooks, we recommend that you set the debughooks setting in the /var/cpanel/cpanel.config file to 3.

This setting outputs a large amount of data. We only recommend this setting on development servers, and not on production servers.

For more information, read our Guide to Standardized Hooks - Debug Mode and The cpanel.config File documentation.

Register the hook

To register your hook action code, run the /usr/local/cpanel/bin/manage_hooks utility.


If you have already registered your hook once, you must use the /usr/local/cpanel/bin/manage_hooks utility to delete the hook from the list of registered hooks before you attempt to register it again.

If you see a message that resembles the following example, the hooks registered properly:

Added hook for Category::Event to hooks registry

If you see one of the following messages, the registration process encountered an error. Click on an error message below to for more information.


Most of the /usr/local/cpanel/bin/manage_hooks utility's other errors result from incorrect flags or missing required values. Check to ensure that you ran the utility correctly and included all of the required items, and then run the manage_hooks utility again.

Check for your hook in the server's list of hooks.

Use either of the following methods to view the server's list of registered hooks:

  • To view the list of registered hooks in the interface, navigate to WHM's Manage Hooks interface ( WHM >> Home >> Development >> Manage Hooks ).
  • To view the list of registered hooks on the command line, run the /usr/local/cpanel/bin/manage_hooks list command.

If your hook does not appear in the list, it did not register properly. Return to the Register the hook step and ensure that the /usr/local/cpanel/bin/manage_hooks utility returns a message of success.

Perform an action that triggers the hook.

Use the appropriate interface to trigger your hook. For example, if you created a Accounts::Create hook, use WHM's Create a New Account interface (WHM >> Home >> Account Functions >> Create a New Account) to create a new account.


If your hook's event is an API function, you can use the appropriate API Shell interface to call that function. However, we recommend that you also perform the related action in the cPanel or WHM interface, to make certain that the action uses the hooked API function.

Check the log for your hook's messages

Check the /usr/local/cpanel/log/error_log file for the messages that your hook action code's Cpanel::Logger module objects log.

These messages will resemble the following example:

[2015-06-16 11:08:29 -0500] info [hook] ***** Copy my file before upcp *****
[2015-06-16 11:08:29 -0500] info [hook] ***** Replace the temp file *****
[2015-06-16 11:08:29 -0500] info [hook] ***** Delete the temp file *****

If the correct info messages do not appear in the /usr/local/cpanel/log/error_log file, one of the following problems occurred:

Check for any desired changes from your hook action code.

Check to ensure that your hook action code performed the desired changes. For example, if your hook action code creates a new file, check for that file on the command line.

If you completed testing steps 1 through 5 successfully, but the hook action code does not perform the desired changes, a problem exists within the hook action code itself. Check your code for errors, incorrect logic, and other problems.

Repeat the hook action for as many scenarios as possible

To increase the chance that you will discover bugs while you test your code, trigger the hook action code under as many different conditions as possible. For example, try to trigger the code in a way that will cause an error, or with different settings enabled or disabled on the server.

Troubleshoot common issues

WARNING: No "describe" pattern found in module.


When you attempt to use the /usr/local/cpanel/bin/manage_hooks utility, you see the WARNING: No "describe" pattern found in module. error message.


  • If you did not include the describe() method in your hook action code, either add it, or run the /usr/local/cpanel/bin/manage_hooks utility again with the required additional options.
  • If your hook action code does include a describe() method, your script or module may not compile correctly. For Perl modules, run the perl -c command, where represents the full module path, to view compilation errors. Fix any errors, and then attempt to run the /usr/local/cpanel/bin/manage_hooks utility again.

This script may only be executed by root


When you attempt to use the /usr/local/cpanel/bin/manage_hooks utility, you see the This script may only be executed by root error message.


Make certain that you SSH in to the server as the root user before you attempt to run the /usr/local/cpanel/bin/manage_hooks utility. Other users cannot run this utility.

WARNING: Can't locate in @INC


When you attempt to use the /usr/local/cpanel/bin/manage_hooks utility to register hook action code in a Perl module, you see the WARNING: Can't locate in @INC error message.


In most cases, this error indicates that you saved the hook action code to an incorrect location. Make certain that you saved it to one of the following locations on your development server:

  • /usr/local/cpanel
  • /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/cpanel_lib/x86_64-linux-64int
  • /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/cpanel_lib
  • /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/5.14.4/x86_64-linux-64int
  • /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/5.14.4
  • /opt/cpanel/perl5/514/site_lib/x86_64-linux-64int
  • /opt/cpanel/perl5/514/site_lib
  • /var/cpanel/perl5/lib
  • /var/cpanel/perl5/lib

For more information about cPanel & WHM's Perl environments, read our Guide to Perl documentation.

Hook action code does not log messages when it runs


No log messages appear in the /usr/local/cpanel/log/error_log file after you perform an action to trigger a hook.


This problem is often due to one of the following problems:

  • Your hook action code does not use the Cpanel::Logger module to log messages to the / usr/local/cpanel/log/error_log file. Check your code to ensure that it logs messages correctly, and then repeat these testing steps. {#nolog}
  • An error occurred before the first message logged. Add more logging instances to your code to locate the error. For example, you may wish to add a log message between every action that your code performs. {#errorbeforelog}
  • You added a post hook for a cPanel UAPI function, and the hooked event failed. The system does not run post hooks when the hooked UAPI function fails. {#postuapi}
  • The action that you performed did not trigger the hook. {#didnottrigger} The cPanel and WHM interfaces call a variety of functions from all of our APIs, and may not always use the version of our API that you expect. To resolve this problem, you can use either of the following methods to identify the correct API function:
    • If your browser includes a Developer Tools or Inspect Elements view, use it to monitor the network stack of requests in order to find the specific function that the interface calls.
    • Check the hooked function's documentation for newer and legacy equivalents. Then, create hooks for all of these API functions and attempt to trigger the hook again.
    Note: If you use this method, we recommend that you retain the hooks for newer equivalents, to ensure that your code continues to function when we eventually upgrade to use the newer functions.