Command died with status 255 on piping attempt

Searching for "Command died with status 255" didn't give many options to further investigate, so filing a new forum topic.

Piping on a Virtualmin website was working just fine, but because nobody could help us with https://virtualmin.com/node/33143, we have migrated this website to freshly installed Cloudmin VPS. Used the native to Virtialmin Backup and Restore feature to do that. In other words, the virtual server has been moved with all the original settings, including mail aliases, which worked for piping purposes just fine before.

Unfortunately, on the new server it is giving the following error:

May 13 22:40:32 my postfix/local[18337]: DB4C11A3F9: to=<support-domain.com@my.domain.com>, orig_to=<support@domain.com>, relay=local, delay=0.37, delays=0.21/0.01/0/0.15, dsn=5.3.0, status=bounced (Command died with status 255: "php /home/domain/domains/my.domain.com/public_html/plugins/support_manager/pipe.php")

Procmail is delivering to other local e-mail destinations without any issues. It is just piping doesn't work anymore. All the file permissions are set correctly. Any thoughts on this?