Today we discovered a weird issue in one cPanel box, it was having a strange Apache error and it was crashing on and on. We checked the logs and found this error: Resource temporarily unavailable: setuid: unable to change to uid:
[Tue Apr 27 10:01:03 2016] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 99 [Tue Apr 27 10:01:03 2016] [alert] Child 14231 returned a Fatal error... Apache is exiting! [Tue Apr 27 10:01:03 2016] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 99 [Tue Apr 27 10:01:03 2016] [emerg] (42)Identifier removed: couldn't grab the accept mutex [Tue Apr 27 10:01:03 2016] [emerg] (23)Invalid argument: couldn't release the accept mutex
Reading a little bit on cPanel forums and according to cPanel Tech Team, this this error can happen because low system memory or file handlers.
How can I fix Apache Resource temporarily unavailable: setuid: unable to change to uid error?
A possible work around for cPanel servers is to apply the following changes to httpd.conf configuration file:
nano -w /usr/local/apache/conf/httpd.conf
This must be placed above the <IfModule prefork.c> block:
AcceptMutex fcntl
Save the changes:
/usr/local/cpanel/bin/apache_conf_distiller --update /scripts/rebuildhttpdconf /etc/init.d/httpd restart
If your httpd service doesn’t start ok after that, try killing the remaining httpd process, like this, and then start the server again:
killall -9 httpd /etc/init.d/httpd restart
This should fix your Resource temporarily unavailable: setuid: unable to change to uid error on Apache. Please let us know if you know any other alternative solutions.
Further reading: mpm_common Apache module