“EXCEPTION decrypt_data: HMAC does not match encrypted data!” Error when running wadminep

When I run the ‘wadminep <ep_name> view_version’ command I get the following:

Performing browse mode 'view_version' on endpoint 'ep_name’
EXCEPTION
decrypt_data: HMAC does not match encrypted data!

Contributed By: Cliff Hobbs [MVP SMS]
There are various Tivoli Knowledge Base Articles on this problem which has many causes some of which are:

The encryption key held by the Endpoint doesn’t match that held on the Gateway/ Endpoint Manager
Two Endpoints having the same Endpoint label (Tivoli doesn’t know which one you’re trying to talk to)
You’re running multiple Endpoints on one machine
An Endpoint was migrated to a different Gateway and the migration process didn’t complete successfully
An Endpoint Primary Gateway is unavailable so the Endpoint logs into it’s backup Gateway. When the Primary Gateway comes back online it tries to communicate with the Endpoint
The DHCP/ IP address of the Endpoint has changed

To fix this problem first try removing old Endpoint entries at the Gateway and then stopping and starting the Endpoint service. If this doesn’t work then delete the Endpoint using the 'wdelep' command from the Tivoli Command Line. Ensure that the ‘epmgr_flags’ flag on the epmgr is set to ‘1’ so that the Endpoint can login as an orphan.