Running the command Get-MailboxDatabaseCopyStatus * on an Exchange 2010 Server that has Exchange 2016 in the environment, returns all the database copies for every version but today Exchange 2010 gave a weird error:

A server-side administrative operation has failed. Operation failed with message: Error 0xe0434f4d (Unknown error ….

This is what you get in the Exchange Management Shell on the Exchange 2010 server:

Now if we head over to the Exchange 2016 Server and run the same command this is the result:

As we can see the copy is in a failed state and in the first command the second Exchange 2016 Server was reporting fine. After fixing the copies by using the update-mailboxdatabase command and we now re-ran the command on the Exchange 2010 server, this is the result:

Now from the Exchange 2010 server all is showing fine again.

Hope it helps.