After upgrading the Exchange 2013 server to CU13 we have the problem that trying to logon to OWA or ECP we getting the logon screen back. We have done several action in trying to resolve this after reading several blogs and articles: - remove and renew the virtual directories
- renew the server certificate
- install .NET Framework 4.6.1
- install CU15
- check web.config files
We have found a workaround by disabling FBA and enable Windowsauthentication.
We even have submitted a case with Microsoft where they have found that is a certificate that is having a bad key
11:41:38.594 14024 7784 HttpProxy Verbose "[FbaModule::ParseCadataCookies] Received CryptographicException System.Security.Cryptography.CryptographicException: Bad Key.
at System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr)