While you migrate users to Exchange Online, an E-Discovery search fails and returns a "Deserialization of type Microsoft.Exchange.Data.ExchangeObjectVersion blocked due to NotInAllow at location MailboxDataStore." error message. This error occurs because E-Discovery search requirements block the mailboxes from being migrated.
To fix this issue, install the following cumulative update, as appropriate:
Learn about the terminology that Microsoft uses to describe software updates.