Symptoms
In rare cases the MSExchangeRepl service stops responding and returns a "Deserialization blocked at location HaRpcError" exception on the server that hosts a passive mailbox database copy. This error might occur after the certificate signing of PowerShell serialization payloads feature is enabled.
Resolution
To fix this issue, install the following cumulative update:
Cumulative Update 14 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019
