This counts CCMs received by this MEP that themselves signaled an Error CCM defect condition, which per 802.1ag/Y.1731 covers a family of CCM-parameter mismatches, such as a receiving MEP getting a CCM whose interval, MEG level, or VLAN does not match its own configuration, reported or detected as a defect. This is one of the highest-priority CFM faults an admin monitors, since Error CCM typically indicates a genuine misconfiguration between the two ends of a service rather than a transient network blip, and it usually needs a configuration fix rather than a network fix to resolve. If this counter starts climbing right after a remote peer's CCM interval was changed without updating this side, that is exactly the mismatch this fault is designed to catch.