Exchange 2016 OWA Fails to Login

And how to fix it

The Problem

I had to set up a forms based authentication Exchange 2016 server for OWA so that hourly workers at my company could log into at a kiosk.

Unfortunately after they logged in, they were greeted with this error message:

“Something went wrong. We can’t get that information right now. Please try again later. X-FEServer MyServer”

I have blurred the server name for X-FEServer, but it was the short name of the Exchange server.

Looking at the Logs

Looking for answers, I discovered there were log files in: C:\Program Files\Microsoft\Exchange Server\V15\Logging\HttpProxy\Owa

I found an Exception error in the logs corresponding to my failed login attempts.

UnexpectedException=Microsoft.Exchange.Diagnostics.ExAssertException: ASSERT: HMACProvider.GetCertificates:protectionCertificates.Length<1

It was part of a much larger line of logging:

2022-04-14T19:01:56.678Z,84199fbc-fc5c-4ea3-9848-9199faffe6b1,15,1,2308,27,,Owa,localhost,/OWA/auth.owa,,FBA,true,MYDOMAIN\HealthMailboxa93375b,,Sid~S-1-5-21-448539723-2052111302-1801674531-102098,AMProbe/Local/ClientAccess,127.0.0.1,MYSERVER,500,,,POST,,,,,WindowsIdentity,,,,359,,,,0,1,,0,,0,,0,0,,0,3,0,,,,,,,,,0,1,1,,2,,2,2,,,,BeginRequest=2022-04-14T19:01:56.676Z;CorrelationID=<empty>;ProxyState-Run=None;FEAuth=BEVersion-1942063364;ProxyState-Complete=CalculateBackEnd;SharedCacheGuard=0;EndRequest=2022-04-14T19:01:56.678Z;,UnexpectedException=Microsoft.Exchange.Diagnostics.ExAssertException: ASSERT: HMACProvider.GetCertificates:protectionCertificates.Length<1    at Microsoft.Exchange.Diagnostics.ExAssert.AssertInternal(String formatString  Object[] parameters)    at Microsoft.Exchange.Diagnostics.ExAssert.RetailAssert[T1 T2](Boolean condition  String formatString  T1 parameter1  T2 parameter2)    at Microsoft.Exchange.Clients.Common.HmacProvider.GetCertificates()    at Microsoft.Exchange.Clients.Common.HmacProvider.GetHmacProvider()    at Microsoft.Exchange.Clients.Common.HmacProvider.ComputeHmac(Byte[][] messageArrays)    at Microsoft.Exchange.HttpProxy.FbaModule.SetCadataCookies(HttpApplication httpApplication)    at…