A typical error for this issue looks like this:
Fatal error: Uncaught exception 'RuntimeException' with message 'SplFileInfo::isDir(): open_basedir restriction in effect. File(/tmp/..) is not within the allowed path(s)In order to resolve this issue, you can try a few different steps:
1. Add the path to your system tmp folder to the open_basedir list of approved folder paths by adding or editing the variable open_basedir in your php.ini file to include the path to your system tmp folder.
2. Disable open_basedir in your php.ini file by removing or commenting out the variable.
3. If you are running PHP 5.5.0 or above, you can try redefining the path to the system tmp folder by adding the line sys_temp_dir = /path/to/new/folder/ to your php.ini file, pointing to a folder within your WHMCS directory.
Note; You can implement the PHP changes for only WHMCS by creating a new php.ini file with the new variables within your WHMCS directory and adding the line suPHP_ConfigPath /path/to/folder/ to your .htaccess file. If you choose to create a custom php.ini file, it is recommended to copy the currently functioning php.ini file to the new folder location and start editing from there.