Common issues related to .NET Core Applications monitoring

Extra random garbage value

Problem

There may be extra random garbage value for instance name in ASP.NET Applications widget and Attribute Details tab for ASP_NET_Apps_Filter / KQE_ASP_NET_APPS_ERROR_FILTER for a short duration.

Solution

The symptom can be safely ignored as there is no data loss. You can restart the IIS service if you wish to remove the extra random garbage value immediately.

Additional application issues

If the .NET Core Application that needs to be monitored does not work through IIS, you could check the handler mappings in IIS and ensure the ASP .NET Core is enabled and mapped to AspNetCoreModuleV2.
If you are unable to access the handler mappings or modules in IIS, you could repair the Microsoft .NET Core 3.1.2 Windows server hosting from Programs and Features by performing the following steps:
1. Launch Control Panel.
2. Navigate to Uninstall a program.
3. Right click Microsoft .NET Core 3.1.2 Windows server hosting and select Change Options.
4. Click Repair.
If you encounter the errors for your application like HTTP Error 500.31- ANCM Failed to Find Native dependencies, ensure that the application is published in self-contained mode; Or if the application is published in framework dependent mode, ensure the supported .NET Core Runtime version is installed on agent machine.

Create a new environment variable ASPNETCORE_ENVIRONMENT under the tag <aspNetCore> and set its value to Development in the file web.config of .NET Core Application. It would provide more detail description for your applications to resolve the issues.

Note: The file web.config is located in the published folder of the application.

<aspNetCore processPath="dotnet" arguments=".\AspDotNetCoreApp.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="inprocess">
            <environmentVariables>
                <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Development" />
            </environmentVariables>
        </aspNetCore>

If all above attempts do not resolve the issue, perform the following steps:
1. Stop the agent services from IBM Performance Management window
2. Launch a command prompt from the path APM_HOME\qe\bin in administrator mode and stop DotNetProfilerService by running the following command:
```
net stop DotNetProfilerService
```
  Where APM_HOME is the agent installation directory.
3. Run the following command to stop the IIS:
```
iisreset /stop
```
4. Revert all the .NET Core Applications to the original state. Refer to Disabling Modules for .NET Core Applications.
5. Run the following commands to unregister the components:
```
configdc unregisterdc all
configdc unregisterdc rtmodule
```
6. Run the following command to start IIS:
```
iisreset /start
```
7. Run the following command to stop the IIS:
```
iisreset /stop
```
8. Run the following commands to register the components:
```
configdc registerdc all
configdc registerdc rtmodule
```
9. Start the DotNetProfilerService and agent services.
10. Enable support for .NET Core Applications. Refer to Enabling Support for .NET Core Applications Monitoring.
11. Restart the .NET Core Application and ensure the application works successfully in IIS.