If you are provisioning servers using Runcloud.io, you may encounter an error with WordPress updates of core or plugins due to the following error:

Fatal error: Uncaught Error: Call to undefined function set_time_limit()

This error occurs in the WordPress file wp-admin/includes/class-core-upgrader.php and for me it only occurred when the web app was set to use PHP 8.0, yet worked fine on PHP 7.4.

The reason this is happening is that RunCloud disables a list of PHP functions on the server by default.

The solution for me was to edit this list of disabled functions and remove set_time_limit from the list.

RunCloud has a knowledge base article about these disabled PHP functions.

I have also sent a ticket to RunCloud, expressing concern that their default settings break the most popular PHP application.

In the meantime, I’ll have to make note of this for my steps when setting up a new application in RunCloud.