This suggests that apache did not properly restart because it found a pid already existing.
The problem with apache not restarting properly due to a timing issue between stopping and starting again was something found in CU181.
See
https://community.ipfire.org/t/upgrade-to-181-hangs-no-webgui/10634
You can confirm this by running
/etc/rc.d/init.d/apache status
If you get
/usr/sbin/httpd is not running.
it indicates that apache did not properly restart.
Run
/etc/rc.d/init.d/apache start
which should then restart it which can be confirmed by
/etc/rc.d/init.d/apache status
which should then give something like:-
httpd is running with Process ID(s) 16120 16118 16117.
except that your PID’s will be different.