Required Function Errors

Problem

You see the following error in the Admin Area:

Required function is not available

Typically, this error will include the name of the function. For example:

Required function base64_decode is not available

Cause

This error indicates that a necessary function is not installed on the server or is disabled in the configuration.

For example, in the section above, the base64_decode function is missing or disabled.

This often occurs with the following cURL functions:

  • curl_init
  • curl_setopt
  • curl_exec
  • curl_getinfo
  • curl_error
  • curl_close

All of these functions must be installed and enabled on your server in order to properly validate your license.

Solution

This troubleshooting information only applies to self-hosted WHMCS installations.

Install the function if it is not available, and then adjust your configuration to enable the function.

For more information, see the applicable documentation:

troubleshooting troubleshooting-article php

Last modified: 2025 October 17