Horde is unable to load; "Class 'Horde\Socket\Client' not found."

Symptoms

When accessing webmail, you see Horde does not open and reports "Class 'Horde\Socket\Client' not found."
 

Description 

When the PHP socket is not available, you may see errors related to "Class 'Horde\Socket\Client' not found."
 

Workaround

You will want to verify that the RPMs are installed for Horde. You can do this through the command-line by running the following script: /scripts/check_cpane_rpms --fix.