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: