This issue occurs when Federal Information Processing Standards (FIPS) for Response Group Service (RGS) is enabled in a Microsoft Skype for Business Server 2015 environment.
Additionally, when you establish application endpoints, you may see the following exception:
sip:RtcApplication-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX@domain.com
sip:RtcApplication- XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX@domain.com
sip:RtcApplication- XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX@domain.com
Exception: System.Reflection.TargetInvocationException - System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.InvalidOperationException: This implementation is not part of the Windows Platform FIPS validated cryptographic algorithms.
at System.Security.Cryptography.SHA512Managed..ctor()
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Security.Cryptography.CryptoConfig.CreateFromName(String name, Object[] args)
at System.Security.Cryptography.SHA512.Create()
at Microsoft.Rtc.Acd.Common.ConsistentHash`2..ctor(Func`2 nodeToHashKeyConverter, Func`2 requestToHashKeyConverter, Int32 virtualNodesMultiplier)
at Microsoft.Rtc.Acd.MatchMaking.PresenceProvider.PresenceComponent.Initialize(IReadOnlyCollection`1 presenceEndpoints, Int32 maxRgsAgentsPerPresenceWatcher)
at Microsoft.Rtc.Acd.MatchMaking.MatchMakingService.Start(IReadOnlyCollection`1 presenceEndpoints)
at Microsoft.Rtc.Acd.AepManager.StartMMAndItsDependencies(IReadOnlyCollection`1 presenceEndpoints)
Cause: Failed to connect to Front End server or the Front End server is misconfigured.
Resolution: Check the Front End server for errors.