"Minor code may provide more information (Keytab FILE:/etc/httpd/example.keytab is nonexistent or empty)" when configuring Apache httpd with mod_auth_gssapi

Issue

Followed the instructions in Configuring SSO in RHEL Apache HTTPD using mod_auth_gssapi, but it is not working with following error in the httpd/error_log:

[auth_gssapi:error] [pid 556351:tid 140111891064576] [client 10.10.10.10:60724] GSS ERROR gss_acquire_cred[_from]() failed to get server creds: [Unspecified GSS failure.  Minor code may provide more information (Keytab FILE:/etc/httpd/example.keytab is nonexistent or empty)]