Released: April 2021 Exchange Server Security Updates

Hello Nino Bilic

after not hearing from you for so long I finally applied security path of April 13th  on my staging and production Exchange 2019 CU9 this Thursday and everything works fine.

One common event warning I noticed before and after applying the patch is this. If you anyone experienced the same then please update.

Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 5/22/2021 7:46:56 AM
Event time (UTC): 5/22/2021 3:46:56 AM
Event ID: c2abd3c344584b7599413857078a5301
Event sequence: 6
Event occurrence: 5
Event detail code: 0

Application information:
Application domain: /LM/W3SVC/1/ROOT/owa-1-132659982733500338
Trust level: Full
Application Virtual Path: /owa
Application Path: C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa\
Machine name: EXMAILSVR

Process information:
Process ID: 812
Process name: w3wp.exe
Account name: NT AUTHORITY\SYSTEM

Exception information:
Exception type: ArgumentException
Exception message: 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__278_0()
at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2 filterDelegate, Action`1 catchDelegate)
at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.CallThreadEntranceMethod(Action method)

Request information:
Request URL: https://public:443/owa/auth/x.js
Request path: /owa/auth/x.js
User host address: 192.168.1.1
User:
Is authenticated: False
Authentication Type:
Thread account name: NT AUTHORITY\SYSTEM

Thread information:
Thread ID: 121
Thread account name: NT AUTHORITY\SYSTEM
Is impersonating: False
Stack trace: 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__278_0()
at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2 filterDelegate, Action`1 catchDelegate)
at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.CallThreadEntranceMethod(Action method)


Custom event details: