Unable to rebuild or restart the Apache configuration: Invalid Mutex directory

Symptoms

• Apache fails to start, and /scripts/restartsrv_httpd returns the following error:

  CONFIG_TEXT: AH00526: Syntax error on line 159 of /etc/apache2/conf/httpd.conf: 
  Invalid Mutex directory in argument file:/run/apache2

• Running /usr/local/cpanel/scripts/rebuildhttpdconf fails with the following error:

  CONFIG_TEXT: Configuration problem detected on line 152 of file /etc/apache2/conf/httpd.conf.work.xxxxxxx: 
  Invalid Mutex directory in argument file:/run/apache2 
  152 ===> Mutex file:/run/apache2 rewrite-map <===

   

Cause

The directory /run/apache2 specified in the Mutex directive, does not exist on the server. This is known to occur when a cPanel ELevate upgrade fails partway through, leaving some system users and groups incomplete.

Resolution

1. Log into the server via SSH

2. Check whether the nobody group exists:

   # getent group nobody

3. If the command returned no output, create a backup copy of the group files:

   # cp -a /etc/group /etc/group.bak 
   # cp -a /etc/gshadow /etc/gshadow.bak

4. If the command returned no output, create the group:

   # groupadd nobody

5. Create the missing directory and set its group and permissions:

   # mkdir /run/apache2 
   # chgrp nobody /run/apache2/ 
   # chmod 710 /run/apache2/

6. Rebuild the Apache configuration and confirm it completes successfully:

   # /usr/local/cpanel/scripts/rebuildhttpdconf 
    

   Note: The following is returned on successful rebuild: 
   Built /etc/apache2/conf/httpd.conf OK