If you want to use this file, the server must be running Linux X64 and proc_open must be allowed.
To verify those requirements, go to https://www.yoursite.com/admin.php?tools/phpinfo and check System and disable_functions:
If the requirements are met, upload the file pyftsubset in binary mode, make sure it is chmoded executable for the user running PHP and configure FAM accordingly.
This binary should only be used if pyftsubset cannot be installed otherwise.
Compatible XF Versions 2.2