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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


Microsoft has confirmed that this is a known issue in the products that are listed in the "Applies to" section, and is working on a solution to address it. The failure of these probes should not cause Exchange Server to experience any functional issues, and you can safely ignore this issue until it can be fixed. 


To work around this issue, temporarily disable the OwaDeepTestMonitor and EacBackEndLogonMonitor monitors. To do this, run the following commands to create a global monitoring override that will apply to all Exchange servers and will expire after 60 days:

Add-GlobalMonitoringOverride -Identity OWA.Protocol\OwaDeepTestProbe -ItemType Probe -PropertyName Enabled -PropertyValue 0 -Duration 60.00:00:00 

Add-GlobalMonitoringOverride -Identity ECP\EacBackEndLogonProbe -ItemType Probe -PropertyName Enabled -PropertyValue 0 -Duration 60.00:00:00


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