Migration Agent for Exchange (MAgE) shows the following error in the log:
Error Dell.MigrationManagerForExchange.Shared.Heart.MailboxPropertyIsNotSetException: Property 'homeMDB' of the mailbox '[Mailbox_GUID] is not set. The mailbox will not be processed.
at Dell.MigrationManagerForExchange.API.Implementation.Mailbox..ctor(String alias, String homeMdb, String ledn, String name, Guid objGuid, Boolean isMoveRequestCollection)
at Dell.MigrationManagerForExchange.Shared.Database.SqlMailboxStorage.Load(Int32 id)
at Quest.MigrationManager.Exchange.Agent.Jobs.DisPlusO365JobBase.SetGeneralVariables()
at Quest.MigrationManager.Exchange.Agent.Jobs.DisPlusO365JobBase.Initialize(EventArgs itemArgs)
at Quest.MigrationManager.Exchange.Agent.Jobs.QJobFactory.Initialize(QJobBase job, NextQueueItemEventArgs itemArgs)
at Quest.MigrationManager.Exchange.Agent.Jobs.QJobFactory.CreateJob(NextQueueItemEventArgs itemArgs)
at Quest.MigrationManager.Exchange.Agent.Tasks.QTaskFactory.CreateTask(NextQueueItemEventArgs itemArgs)
at Quest.MigrationManager.Exchange.Agent.QTaskManager.CreateTask(IAssignment asmnt)
at Quest.MigrationManager.Exchange.Agent.QTaskManager.PickNextAssignment()
at Quest.MigrationManager.Exchange.Agent.QTaskManager.MailboxThread()