When upgrading from Sentinel 31.0.4 to Sentinel 31.0.6, the sentinel.service file isn’t updated and tries to start the service from /etc/init.d/sentinel, but the file no longer exists there but rather at /opt/sentinel/bin/sentinel.

Doing a clean install of Sentinel 31.0.6 also does not generate an appropriate service file that points to /opt/sentinel/bin/sentinel.

My testing was done with RHEL9, but this likely affects all other RHEL based distros. Debian/Ubuntu seem to be properly configured,

Further detail from testing on RHEL9:
On a test system, I did an install of Sentinel 31.0.4 and then upgraded it to 31.0.6 and here are my findings.

The /etc/init.d/sentinel script exists:

The Sentinel service references /etc/init.d/sentinel and is being run from there:

There is no /opt/sentinel/bin/sentinel file:

With Sentinel 31.0.6, the /etc/init.d/sentinel file does not exist:

The Sentinel service still references /etc/init.d/sentinel, but that file doesn't exist:

The Sentinel executable does exist at /opt/sentinel/bin/sentinel:

The user would either need to modify the service file to point to /opt/sentinel/bin/sentinel or copy/make a symbolic link of that file to be at /etc/init.d/sentinel.

The service file should ultimately be updated to point to /opt/sentinel/bin/sentinel similar to how other service file units work to more natively work with systemd.