Restarting IPA services gives an error "Starting pki-ca: Error code 4"

Issue

• Restarting IPA services gives an error Starting pki-ca: Error code 4

# ipactl start
Starting Directory Service
Starting dirsrv:
    EDC-LAFARGEONE-NET...                                  [  OK  ]
    PKI-IPA...                                             [  OK  ]
Starting KDC Service
Starting Kerberos 5 KDC:                                   [  OK  ]
Starting KPASSWD Service
Starting Kerberos 5 Admin Server:                          [  OK  ]
Starting MEMCACHE Service
Starting ipa_memcached:                                    [  OK  ]
Starting HTTP Service
Starting httpd: [Sun Nov 17 05:10:06 2013] [warn] worker ajp://localhost:9447/ already used by another worker
[Sun Nov 17 05:10:06 2013] [warn] worker ajp://localhost:9447/ already used by another worker
                                                           [  OK  ]
Starting CA Service
Starting pki-ca: Error code 4                              [FAILED]
Failed to start CA Service
Shutting down
Stopping Kerberos 5 KDC:                                   [  OK  ]
Stopping Kerberos 5 Admin Server:                          [  OK  ]
Stopping ipa_memcached:                                    [  OK  ]
Stopping httpd:                                            [  OK  ]
Stopping pki-ca:                                           [  OK  ]
Shutting down dirsrv:
    EDC-LAFARGEONE-NET...                                  [  OK  ]
    PKI-IPA...                                             [  OK  ]
Aborting ipactl

• IPA services fails to start.