The cman service could not start with 'Relax-NG parser error'/'Relax-NG validity error' after updating the RHEL cluster

Issue

• The cman service could not start after updating the RHEL version from 6.0 to RHEL6.3

• The cman service could not start after updating the RHEL version from 6.6 to RHEL6.7

• Start the cman service and show the error messages below

# service cman start
Starting cluster: 
   Checking if cluster has been disabled at boot... [  OK  ]
   Checking Network Manager... [  OK  ]
   Global setup... [  OK  ]
   Loading kernel modules... [  OK  ]
   Mounting configfs... [  OK  ]
   Starting cman... 
/usr/share/cluster/cluster.rng:998: element ref: Relax-NG parser error : Reference VM has no matching definition
/usr/share/cluster/cluster.rng:995: element ref: Relax-NG parser error : Reference SERVICE has no matching definition
/usr/share/cluster/cluster.rng:995: element ref: Relax-NG parser error : Internal found no define for ref SERVICE
/usr/share/cluster/cluster.rng:998: element ref: Relax-NG parser error : Internal found no define for ref VM
Relax-NG schema /usr/share/cluster/cluster.rng failed to compile
[  OK  ]
   Waiting for quorum... [  OK  ]
   Starting fenced... [  OK  ]
   Starting dlm_controld... [  OK  ]
   Starting gfs_controld... [  OK  ]
   Unfencing self... [  OK  ]
   Joining fence domain... [  OK  ]

or

# service cman start
Starting cluster: 
   Checking if cluster has been disabled at boot...        [  OK  ]
   Checking Network Manager...                             [  OK  ]
   Global setup...                                         [  OK  ]
   Loading kernel modules...                               [  OK  ]
   Mounting configfs...                                    [  OK  ]
   Starting cman... Relax-NG validity error : Extra element fencedevices in interleave
tempfile:23: element fencedevices: Relax-NG validity error : Element cluster failed to validate content
tempfile:16: element device: validity error : IDREF attribute name references an unknown ID "fence_pc02"
Configuration fails to validate
                                                           [  OK  ]
   Starting qdiskd...                                      [  OK  ]
   Waiting for quorum...                                   [  OK  ]
   Starting fenced...                                      [  OK  ]
   Starting dlm_controld...                                [  OK  ]
   Tuning DLM kernel config...                             [  OK  ]
   Starting gfs_controld...                                [  OK  ]
   Unfencing self...                                       [  OK  ]
   Joining fence domain...                                 [  OK  ]

• Copying a clean cluster.rng or doing yum reinstall cman manually doesn't solve the issue.