MSExchange Autodiscover event id 1

[BigJOE]

Добрый день! Смотрю на серверах Exchange ошибки и варнинги. Наткнулся на интересный алерт:

Unhandled Exception "Object reference not set to an instance of an object."
Stack trace: at Microsoft.Exchange.AutoDiscoverV2.FlightSettingRepository.GetHostNameFromVdir(ADObjectId serverSiteId, String protocol)
at Microsoft.Exchange.AutoDiscoverV2.AutoDiscoverV2.ExecuteOnPremEndFlow(AutoDiscoverV2Request request)
at Microsoft.Exchange.AutoDiscoverV2.AutoDiscoverV2.Execute(AutoDiscoverV2Request request, ITenantRepository tenantRepository)
at Microsoft.Exchange.AutoDiscoverV2.AutoDiscoverV2HandlerBase.<>c__DisplayClass11_0.<ProcessRequest>b__0()
at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2 filterDelegate, Action`1 catchDelegate)

Watson report about to be sent for process id: 15336, with parameters: E12IIS, c-RTL-AMD64, 15.02.1544.011, w3wp#MSExchangeOWAAppPool, M.E.Data.ApplicationLogic, M.E.D.A.C.BackEndServer.FromString, System.ArgumentException, a995-dumptidset, 15.02.1544.011.
ErrorReportingEnabled: True

[Owa] An internal server error occurred. The unhandled exception was: System.ArgumentException: Invalid input value
Parameter name: input
at Microsoft.Exchange.Data.ApplicationLogic.Cafe.BackEndServer.FromString(String input)
at Microsoft.Exchange.HttpProxy.OwaResourceProxyRequestHandler.ResolveAnchorMailbox()
at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.InternalBeginCalculateTargetBackEnd(AnchorMailbox& anchorMailbox)
at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.<BeginCalculateTargetBackEnd>b__279_0()
at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2 filterDelegate, Action`1 catchDelegate)

События регистрируются на Exchange server 2019 + DAG
Подскажите о чем эта ошибка и куда копать ?