Exim fails to start with error on Ubuntu 22.04: Failed with result 'protocol'.

Symptoms

Exim won't start and the following error is logged:

systemd[1]: exim.service: Failed with result 'protocol'.

Description

This occurs due to missing data in /etc/sysconfig/exim. The expected data is saved to /etc/sysconfig/exim.dpkg-dist. The missing data results in the 'protocol' error.

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-46038. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

Run the following commands as the root user via SSH:

mv /etc/sysconfig/exim{,.$( date +%Y%m%d )}

mv /etc/sysconfig/exim.dpkg-dist /etc/sysconfig/exim