Also /var/log/apache2/error_log might tell you what the problem is - depending on the issue, you can just “less” it or “tail” it in another terminal window, for example:
sudo tail -f /var/log/apache2/error_log
and issue sudo systemctl start apache2 in another terminal window. CTRL+C to exit the tail.
Thank for the prompt answer!
I did what you told and corrected some issues but this one:
Jan 31 09:01:08 linux.site start_apache2[22528]: Invalid command 'which', perhaps misspelled or defined by a module not included in the server configuration
I looked for some “which” misplaced as a command in httpd.conf but couldn’t find.
Am I looking in the wrong place?