I was facing problems starting httpd on mac using brew. Took me few minutes to figure out what was the actual problem. I thought I will share if you are facing same issue as well.
Starting httpd was fine.
brew services start httpd
..but the httpd error log was showing errors.
tail -f /usr/local/var/log/httpd/error_log
[Sat Apr 03 16:29:44.966179 2021] [core:error] [pid 24658] (13)Permission denied: AH00099: could not create /usr/local/var/run/httpd/httpd.pid
Simple solution was to delete this httpd.pid file.