I have a VM that suddenly stopped allowing snapshots. I first noticed it with errors in Backup Exec. Jobs failed with the following message:
When I try taking a snapshot from the vSphere client, I get the following - "The operation is not allowed in the current state".
I have been searching for a thread that leads in the right direction, but have hit dead ends in every case.
Datastore looks like this:
You can try restarting the management agents on the host where that VM resides on by following this KB-- Restarting the Management agents in ESXi (1003490) | VMware KB
Once the agents restart successfully, try taking another snapshot of the VM.
Let me know the results.