In many cases, it's a load issue on the CA server (e.g. looking up your account's records in the database).
Some things to check that can help:
Does it still happen if you try again shortly after?
Does it still happen if you use a fresh Issuer/ClusterIssuer?
If you are consistently getting the same error on every finalization attempt, then we can tag the staff to look into it, but otherwise I don't think there's much that can be done.
Thanks for the help…it didn’t happen again, but I want to understand what should be the action in case it will happen again.
And if a retry may help here?