Applies To
Exchange Server 2019 Exchange Server 2016

Symptoms 

After the Microsoft Exchange Server March 2024 security update is installed, the OwaDeepTestProbe and EacBackEndLogonProbe probes begin to fail. This triggers an Unhealthy status of the EacBackEndLogonMonitor and OwaDeepTestMonitor monitors. 

Additionally, the following events are logged in the Exchange Server application log: 

---

Source: MSExchange Common 

Id: 4999 

Details: Watson report about to be sent for process id: <id>, with parameters: E12IIS, <buildnumber>, w3wp#MSExchangeOWAAppPool, M.E.C.Owa2.Server, M.E.C.O.S.C.OwaModule.ShouldBlockIncomingRequest

---

Source: Windows Error Reporting 

Id: 1001 

Details: P5: M.E.C.O.S.C.OwaModule.ShouldBlockIncomingRequest 

P6: System.NullReferenceException

Resolution 

To fix this issue, install the following update:

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