Symptoms
When you migrate users to Exchange Online, an E-Discovery search fails and returns the following error message:
Deserialization of type Microsoft.Exchange.Data.Directory.ADMultiValuedProperty`1 blocked due to NotInAllow at location MailboxDataStore.
Cause
This error occurs because E-Discovery search requirements block the mailboxes from being migrated.
Resolution
To fix this issue, install the following cumulative update, as appropriate: