"Unable to cast object of type" error when you try to connect to the Office 365 domain from an on-premises hybrid server
Note The Hybrid Configuration wizard that's included in the Exchange Management Console in Microsoft Exchange Server 2010 is no longer supported. Therefore, you should no longer use the old Hybrid Configuration wizard. Instead, use the Office 365 Hybrid Configuration wizard that's available at http://aka.ms/HybridWizard. For more information, see Office 365 Hybrid Configuration wizard for Exchange 2010.
Consider the following scenario. You have a hybrid deployment of an on-premises Microsoft Exchange server and Exchange Online in Office 365. You try to connect to the Office 365 cloud-based domain by using the Exchange Management Console on the on-premises hybrid server. However, the connection fails, and you receive the following error message:
"Unable to cast object of type 'system.Runtime.Serialization.TypeLoadExceptionHolder' to type'Microsoft.Exchange.Data.RoleEntry'"
This issue occurs if you're trying to connect to Office 365 from an on-premises hybrid server that's running Exchange Server 2010 Service Pack 1 (SP1) or Exchange Server 2010 Service Pack 2 (SP2).
Upgrade your Exchange Server 2010 servers to Exchange Server 2010 Service Pack 3 (SP3). To download Exchange Server 2010 SP3, go to Microsoft Exchange Server 2010 Service Pack 3 (SP3).
This issue is generally seen when Exchange 2010 servers are in a hybrid configuration with an earlier release of Office 365, and then Office 365 is upgraded to the current release. For an Exchange 2010-based hybrid deployment with the current release of Office 365, all on-premises Exchange 2010 servers must be running Exchange 2010 SP3 or a later version.
For more information about how to set up a hybrid deployment with on-premises Exchange 2010 servers and the latest release of Office 365, see Hybrid deployment prerequisites.
For more information about Exchange 2010 SP3, see the following Microsoft Knowledge Base article:
2808208 Description of Exchange Server 2010 SP3Still need help? Go to the Office 365 Community website.
Article ID: 2875125 - Last Review: 04/25/2016 11:20:00 - Revision: 4.0
Microsoft Exchange Online, Microsoft Exchange Server 2010 Enterprise, Microsoft Exchange Server 2010 Standard, Microsoft Exchange Server 2010 Service Pack 1, Microsoft Exchange Server 2010 Service Pack 2
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