MAgE log file shows:
Error Quest.MigrationManager.Exchange.Basis.IsNullException: mailbox:
at Quest.MigrationManager.Exchange.MigrationConnectors.Ews.EwsSyncConnector.Connect()
at Quest.MigrationManager.Exchange.MigrationConnectors.GenericSyncConnector.StartSync(SyncDirection syncType)
at Quest.MigrationManager.Exchange.MigrationConnectors.GenericSyncConnector.ReSync(SyncDirection syncType)
at Quest.MigrationManager.Exchange.Agent.Jobs.DisPlusO365JobBase.<>c__DisplayClass61_0.<DoSync>b__3()
at Dell.MigrationManagerForExchange.General.DotNet.ResultHandler.Execute(Action act, Action onSuccess, Action`1 onFailure, Boolean bSuppressException)
at Quest.MigrationManager.Exchange.Agent.Jobs.DisPlusO365JobBase.DoSync(IMailboxSyncConnectorInternal sourceConnector, IMailboxSyncConnectorInternal targetConnector, String mailboxLedn, IAgentProperties cfg)
at Quest.MigrationManager.Exchange.Agent.Jobs.DisBaseJob.PerformSync()
at Quest.MigrationManager.Exchange.Agent.Jobs.DisPlusO365JobBase.RunJob()