"Failed to start The Apache HTTP Server" after misconfiguring Froxlor - apache

Question

This all started yesterday after I added a second IP address for port 443 to the "ips and ports" list in Froxlor. As soon as Froxlor's cron job ran, Apache failed to restart. Ever since then, nothing I try will get Apache to stay running with SSL enabled in Froxlor.
System Config:
Ubuntu 20.04.2 LTS (focal)
Apache 2.4.41
Froxlor 0.10.27
Output from sudo systemctl start apache2:
Job for apache2.service failed because the control process exited with error code.
See "systemctl status apache2.service" and "journalctl -xe" for details.
Output from systemctl status apache2.service:
● apache2.service - The Apache HTTP Server
Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Mon 2021-07-19 13:33:31 UTC; 41s ago
Docs: https://httpd.apache.org/docs/2.4/
Process: 17629 ExecStart=/usr/sbin/apachectl start (code=exited, status=1/FAILURE)
systemd[1]: Starting The Apache HTTP Server...
apachectl[17641]: AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName'>
apachectl[17629]: Action 'start' failed.
apachectl[17629]: The Apache error log may have more information.
systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
systemd[1]: apache2.service: Failed with result 'exit-code'.
systemd[1]: Failed to start The Apache HTTP Server.
Output from sudo journalctl -u apache2.service --since today --no-pager:
systemd[1]: Starting The Apache HTTP Server...
apachectl[17169]: AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
apachectl[17165]: Action 'start' failed.
apachectl[17165]: The Apache error log may have more information.
systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
systemd[1]: apache2.service: Failed with result 'exit-code'.
systemd[1]: Failed to start The Apache HTTP Server.
systemd[1]: apache2.service: Unit cannot be reloaded because it is inactive.
"Address already in use" error
Initially I was also getting an error that said apachectl[16500]: (98)Address already in use: AH00072: make_sock: could not bind to address on port 443. Running netstat -anp | grep 443 did not reveal any other processes hogging that port, so I suspected that Apache was trying to use port 443 twice (which tracks with my configuration goof). I managed to get into the database and delete the ip/port record (which had not been assigned to any sites yet) and this particular error went away because Froxlor stopped creating an extra conf file containing Listen 443.
If I comment out both instances of Listen 443 within /etc/apache2/ports.conf, then this particular error goes away but Apache still fails to load.
# If you just change the port or add more ports here, you will likely also
# have to change the VirtualHost statement in
# /etc/apache2/sites-enabled/000-default.conf
Listen 80
#<IfModule ssl_module>
# Listen 443
#</IfModule>
#<IfModule mod_gnutls.c>
# Listen 443
#</IfModule>
# vim: syntax=apache ts=4 sw=4 sts=4 sr noet
(This post with a similar issue offered some insight on this bit)
Output from sudo grep "443" /etc/apache2/*
grep: /etc/apache2/conf-available: Is a directory
grep: /etc/apache2/conf-enabled: Is a directory
grep: /etc/apache2/htpasswd: Is a directory
grep: /etc/apache2/mods-available: Is a directory
grep: /etc/apache2/mods-enabled: Is a directory
/etc/apache2/ports.conf:# Listen 443
/etc/apache2/ports.conf:# Listen 443
grep: /etc/apache2/sites-available: Is a directory
grep: /etc/apache2/sites-enabled: Is a directory
Misc. remarks about Froxlor:
If I comment out \Froxlor\Cron\MasterCron::run(); inside of /var/www/froxlor/scripts/froxlor_master_cronjob.php, then the Froxlor cron job is effectively disabled. Can be useful for troubleshooting, but doesn't fix anything.
Running sudo /usr/bin/php /var/www/froxlor/scripts/froxlor_master_cronjob.php --force will trigger Froxlor to execute its cron job immediately
Current Status:
After many hours of troubleshooting, here is what I know:
when no ip is configured with port 443/SSL, Apache will start.
deleting /etc/apache2/sites-enabled/ directory allows Apache to start, until Froxlor's cron job regenerates it.
likewise, just deleting the *.443.conf files and any ssl.conf files from /etc/apache2/sites-enabled/ also temporarily allows Apache to start (until the Froxlor cron job runs)
removing Froxlor from the server allows Apache to start, but the problem comes back immediately after configuring port 443 within Froxlor.
TLDR: Something broke when I opened Froxlor and added a second IP with a port that was already in use (port 443). Now Apache won't start unless I delete any .conf file involving SSH. Removing Froxlor (including deleting the database) and deleting sites-enabled before reinstalling Froxlor did not resolve the issue.
EDIT: Regenerated my security certificates and now all is good.

Answer 1

Ugh... multitasking bit me again.
Apparently there was something off with the local security certificate. I regenerated it and Apache started working again.
Related post here