Migration Agent for Exchange (MAgE) shows the following error in the log file:
Error System.InvalidCastException: Unable to cast object of type 'System.String' to type 'System.Byte[]'.
at Quest.MigrationManager.Exchange.MigrationConnectors.FTStream.<>c__DisplayClass10_0.<Property>b__0(PropertyType scalarPtyp, Object value)
at Quest.MigrationManager.Exchange.MigrationConnectors.FTStream.Property(MAPIProperty prop)
at Quest.MigrationManager.Exchange.MigrationConnectors.MAPI.MAPIMessageConstructor.PushRecipients(Object[] tags, Object[] props)
at Quest.MigrationManager.Exchange.MigrationConnectors.MAPI.MAPIMessageConstructor.PushToStream(IMapiMessage message, MessageType messageType, HashSet`1 excludeTags, List`1& usedTags)
at Quest.MigrationManager.Exchange.MigrationConnectors.MAPI.MAPIMessageConstructor.PushToStream(IMapiMessage message, MessageType messageType)
at Quest.MigrationManager.Exchange.MigrationConnectors.MAPI.MapiSyncConnector.MakeStreamedItem(IItemInfo item, IMapiMessage msg)
at Quest.MigrationManager.Exchange.MigrationConnectors.MAPI.MapiSyncConnector.GetItem(String folderId, IItemInfo item, Action`2 onSkip, Action`2 onFail)
All messages for which the error above is logged will be marked as failed and increase the Failed Items counter in Migration Manager Statistics pane.