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:
Last modified: 2025 October 17