bit of background...

I upgraded this exchange 2010 server from SP1 to SP2 and had issues with web services having paths like file:\\%EXCHANGEINSTALLDIR\BIN in the web.config files so autodiscover, active sync and ews did not work, they generated similar errors to:

Could not load type 'Microsoft.Exchange.Data.Directory.DirectoryBackendType' from assembly 'Microsoft.Exchange.Data.Directory, Version=14.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

I replaced these files from a known working server and this fixed the web services problem.I am wondering what reliance hybrid wizard has on web services and if I have maybe missed a web.config file I need to replace...

Summary: 2 item(s). 1 succeeded, 1 failed.
Elapsed time: 00:00:11

Set-HybridConfiguration
Completed

Exchange Management Shell command completed:
Set-HybridConfiguration -Features 'MoveMailbox','OnlineArchive','FreeBusy','Mailtips','MessageTracking','OwaRedirection','SecureMail' -Domains domain.com -ClientAccessServers server1-TransportServers server1-ExternalIPAddresses 1.1.1.1-OnPremisesSmartHost server1-SecureMailCertificateThumbprint '4C7252AAA9grhrhrthrthrthtrhrth52'

Elapsed Time: 00:00:00

Update-HybridConfiguration
Failed

Error:
Updating hybrid configuration failed with error 'Subtask CheckPrereqs execution failed: Check Prerequisites

Could not load type 'Microsoft.Exchange.Data.Directory.DirectoryBackendType' from assembly 'Microsoft.Exchange.Data.Directory, Version=14.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.
   at System.Reflection.Assembly._GetType(String name, Boolean throwOnError, Boolean ignoreCase)
   at System.UnitySerializationHolder.GetRealObject(StreamingContext context)
   at System.Runtime.Serialization.ObjectManager.ResolveObjectReference(ObjectHolder holder)
   at System.Runtime.Serialization.ObjectManager.DoFixups()
   at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, IMethodCallMessage methodCallMessage)
   at Microsoft.Exchange.Data.SerializationTypeConverter.<>c__DisplayClass3.<DeserializeObject>b__0()
   at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(TryDelegate tryDelegate, FilterDelegate filterDelegate, CatchDelegate catchDelegate)
   at Microsoft.Exchange.Diagnostics.ExWatson.SendReportOnUnhandledException(MethodDelegate methodDelegate, IsExceptionInteresting exceptionInteresting, Boolean terminating)
   at Microsoft.Exchange.Data.SerializationTypeConverter.DeserializeObject(Object sourceValue, Type destinationType)
   at Microsoft.Exchange.Configuration.MonadDataProvider.MonadCommand.Deserialize(PSObject psObject)
   at Microsoft.Exchange.Management.Hybrid.RemotePowershellSession.RunOneCommand(String command, Dictionary`2 parameters, Boolean ignoreNotFoundErrors)
   at Microsoft.Exchange.Management.Hybrid.TaskCommon.GetAcceptedDomains(RemotePowershellSession session)
   at Microsoft.Exchange.Management.Hybrid.GlobalPrereqTask.CheckPrereqs(ITaskContext taskContext)
   at Microsoft.Exchange.Management.Hybrid.Engine.ExecuteTask(TaskBase taskBase, TaskContext taskContext)
'.

Additional troubleshooting information is available in the Update-HybridConfiguration log file located at C:\Program Files\Microsoft\Exchange Server\V14\Logging\Update-HybridConfiguration\HybridConfiguration_7_24_2015_8_3_31_635733218113901372.log.

Exchange Management Shell command attempted:
Update-HybridConfiguration -OnPremisesCredentials 'System.Management.Automation.PSCredential' -TenantCredentials 'System.Management.Automation.PSCredential'

Elapsed Time: 00:00:10

I'm pretty certain that the hybrid configuration wizard is highly reliant on EWS.

I think if I were you, I'd build a new hybrid server and replace that one.

Hi KingMT,

Base on my search, I found a similar thread for your reference, it may give your some hints:

Exchange 2010 on Prem to Exchange 2013 Hybrid with O365

Best regards,

Thanks Ed, I think I will build a new hybrid server as I think troubleshooting this issue will take longer, although I have tested EWS and everything seems fine there...

Niko, this article is to do with installing 2013 and schema incompatibility nothing to do with this scenario...