Can't start MySQL after RHEL upgrade to 7.2, Unregistered Authentication Agent

Question

I just upgraded my RHEL system from 6.7 to 7.2, and am having issues starting up MySQL again.

When running:

# systemctl start mysqld

I get this error:

Job for mysqld.service failed because the control process exited with error code. 
See "systemctl status mysqld.service" and "journalctl -xe" for details.

systemctl status tells me the following:

● mysqld.service - SYSV: MySQL database server.
   Loaded: loaded (/etc/rc.d/init.d/mysqld)
   Active: failed (Result: exit-code) since Tue 2017-05-02 10:00:52 CDT; 59s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 21827 ExecStart=/etc/rc.d/init.d/mysqld start (code=exited, status=1/FAILURE)

May 02 10:00:51 sa-dnca01.zs.local systemd[1]: Starting SYSV: MySQL database server....
May 02 10:00:52 sa-dnca01.zs.local mysqld[21827]: MySQL Daemon failed to start.
May 02 10:00:52 sa-dnca01.zs.local mysqld[21827]: Starting mysqld:  [FAILED]
May 02 10:00:52 sa-dnca01.zs.local systemd[1]: mysqld.service: control process exited, code=exited status=1
May 02 10:00:52 sa-dnca01.zs.local systemd[1]: Failed to start SYSV: MySQL database server..
May 02 10:00:52 sa-dnca01.zs.local systemd[1]: Unit mysqld.service entered failed state.
May 02 10:00:52 sa-dnca01.zs.local systemd[1]: mysqld.service failed.

And then journalctl -xe tells me the following:

May 02 10:03:09 sa-dnca01.zs.local polkitd[768]: Registered Authentication Agent for unix-process:22276:29249716 (system bus name :1.30 [/usr/bin/
May 02 10:03:09 sa-dnca01.zs.local systemd[1]: Starting SYSV: MySQL database server....
-- Subject: Unit mysqld.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysqld.service has begun starting up.
May 02 10:03:10 sa-dnca01.zs.local mysqld[22281]: MySQL Daemon failed to start.
May 02 10:03:10 sa-dnca01.zs.local mysqld[22281]: Starting mysqld:  [FAILED]
May 02 10:03:10 sa-dnca01.zs.local systemd[1]: mysqld.service: control process exited, code=exited status=1
May 02 10:03:10 sa-dnca01.zs.local systemd[1]: Failed to start SYSV: MySQL database server..
-- Subject: Unit mysqld.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysqld.service has failed.
--
-- The result is failed.
May 02 10:03:10 sa-dnca01.zs.local systemd[1]: Unit mysqld.service entered failed state.
May 02 10:03:10 sa-dnca01.zs.local systemd[1]: mysqld.service failed.
May 02 10:03:10 sa-dnca01.zs.local polkitd[768]: Unregistered Authentication Agent for unix-process:22276:29249716 (system bus name :1.30, object

I don't really know what any of this means, but I did have a successfully running MySQL server before the server had an OS upgrade.

Answer 1

Turns out I was getting this error because I hadn't created the necessary logging directory in:

/var/run/mysqld

and given it the proper permissions.

Looking at the log file in /var/log/mysqld.log led me to the issue.