Users always get the FBA page when they access OWA or ECP in Exchange Server 2013

Symptoms

Assume that you use the following command to enable Integrated Windows Authentication or Basic Authentication:

Set-OwaVirtualDirectory “CAS1\owa (Default Web Site)” -WindowsAuthentication $true -BasicAuthentication $trueSet-ECPVirtualDirectory “CAS1\ecp (Default Web Site)” -WindowsAuthentication $true -BasicAuthentication $true

After you do this, FormsAuthentication is displayed as disabled in the Outlook Web Access (OWA) and Exchange Control Panel (ECP) virtual directories:

ClientAuthCleanupLevel : High
BasicAuthentication : True
WindowsAuthentication : True
DigestAuthentication : False
FormsAuthentication : False
LiveIdAuthentication : False
AdfsAuthentication : False
OAuthAuthentication : False
ExternalAuthenticationMethods : {Fba}However, clients keep encountering forms-based authentication (FBA) when they try to log on to OWA or ECP.

Note Clients can log on successfully after they provide the correct credentials.

Resolution

To resolve this issue, install the following cumulative update:

2936880 Cumulative Update 5 for Exchange Server 2013

Workaround

To work around this issue, make sure that you specify -FormsAuthentication $false when you disable FBA and enable other authentication types in the OWA or ECP virtual directories. To do this, follow these steps:

1. Enable forms-based authentication.

   • For OWA, run the following command:
     
     Set-OwaVirtualDirectory -Identity "CAS1\owa (Default Web Site)" -FormsAuthentication $True

   • For ECP, run the following command:
     
     Set-ECPVirtualDirectory -Identity "CAS1\ECP (Default Web Site)" -FormsAuthentication $True

2. Enable the authentication type that you want, and specify -FormsAuthentication $false.
   

   • For OWA, run the following command:
     
     Set-OwaVirtualDirectory -Identity "CAS1\owa (Default Web Site)" -FormsAuthentication $False -WindowsAuthentication $true -BasicAuthentication $true

   • For ECP, run the following command:
     
     Set-ECPVirtualDirectory -Identity "CAS1\ECP (Default Web Site)" -FormsAuthentication $False -WindowsAuthentication $True -BasicAuthentication $True

3. Perform an IISReset operation. For more information about how to do this, see How to restart IIS.