Diagnostics and Troubleshooting


When troubleshooting on a live environment, you would do not have the source code of the application deployed.

Problems: If you encounter any of the following problems:

  • You are not able to log into the Sitefinity instance
  • You get a No contract for communication found error when editing a .NET Core page.
  • You get the Invalid value for identity server host header passed YSOD.

Solution: The above problems are most likely related to incorrectly setup of the .NET Core Renderer application. To fix them, make sure that your Sitefinity CMS instance and your .NET Core Renderer application are correctly set up. Make sure you perform correctly the steps in the Setup procedure.

Solution: Alternatively, you can get more detailed information whether the .NET Core Renderer is set-up correctly, using the Diagnostics section below.

Problem: You are having runtime errors

Solution: You can search the cause of the errors in the logs of the application. To do this, you must access the logs in one of these ways:

  • If you are hosting on Microsoft Windows, you can look in the Application Event Log (IIS).
  • Alternatively, you can add a file system logger to catch the logs. You can implement your own or use a third-party logger, such as Serilog.


If you cannot identify the reason why your Renderer app is not working, you can run the diagnostics page.

  1. Enable the .NET Core Renderer diagnostics.
    To do this, open the web.config file of your Sitefinity CMS instance.
  2. Inside section <configuration> / <appSettings> insert the following:
    <add key="sf:enableRendererDiagnostics" value="true" />
  3. Run the Renderer in debug mode with environment Development.
    If you have not changed it, this is the default value.
  4. Navigate to the diagnostics using the following URL:

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