What could be causing the "open_basedir restriction" error in PHP when moving a website to a new server?

The "open_basedir restriction" error in PHP occurs when the open_basedir directive in the php.ini file restricts access to files outside a specified directory. This can happen when moving a website to a new server with a different file structure. To solve this issue, you can either update the open_basedir directive in the php.ini file to include the necessary directories or disable it altogether.

// Disable open_basedir restriction
ini_set('open_basedir', null);