Symptoms
You can’t use the Test-ExchangeSearch cmdlet for monitoring or testing in Microsoft Exchange Server 2016. Monitoring application by running the Test-ExchangeSearch cmdlet causes the Powershell application pool to crash. In addition, the following error message is logged:
Log Name: Application ​
Source: ASP.NET 4.0.30319.0 ​
Date: DateTime ​
Event ID: 1325 ​
Task Category: None ​
Level: Error ​
Keywords: Classic ​
User: N/A ​
Computer: ComputerName ​
Description: An unhandled exception occurred and the process was terminated. ​
Application ID: DefaultDomain ​
Process ID: 7332 ​
Exception: System.NullReferenceException ​Message: Object reference not set to an instance of an object.
Resolution
To fix this issue, install the Cumulative Update 16 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
References
Learn about the terminology that Microsoft uses to describe software updates.
