"Subtask CheckPrereqs execution failed" error in Hybrid Configuration wizard for Exchange Server 2013
When you use the Hybrid Configuration wizard to create or manage a hybrid environment that includes Microsoft Exchange Server 2013, you receive the following error message:
Subtask CheckPrereqs execution failed: Check Tenant Prerequisites
Deserialization fails due to one SerializationException: Microsoft.Exchange.Compliance.Serialization.Formatters.BlockedTypeException: The type to be (de)serialized is not allowed: Microsoft.Exchange.Data.Directory.DirectoryBackendType
This problem occurs because of recent changes to Exchange Online that prevent the Exchange 2013 Hybrid Configuration wizard from running correctly.
To resolve this problem, follow these steps:
Install the latest cumulative update for Exchange Server 2013. To download this update, go to Updates for Exchange 2013. Run the latest version of the Hybrid Configuration wizard. To download this, go to http://aka.ms/HybridWizard.
For more information about the benefits of the latest Hybrid Configuration wizard, see
Introducing the Microsoft Office 365 Hybrid Configuration Wizard
When you upgrade from Microsoft Exchange Server 2010 to Exchange Server 2013
If you upgraded from Exchange Server 2010 to Exchange Server 2013 and are experiencing the issue that's described in the "Symptoms" section, we recommend that you install the latest cumulative update for Exchange Server 2013. For more information, go to
Updates for Exchange 2013
Article ID: 2988229 - Last Review: 04/26/2016 14:22:00 - Revision: 9.0
Microsoft Exchange Server 2013 Enterprise, Microsoft Exchange Server 2013 Standard
Keywords: kbqfe kbfix kbsurveynew kbexpertiseadvanced o365022013 o365 o365a o365m hybrid KB2988229