ASP.NET Core Diagnostics for IIS/IIS Express

By Lex Li

This page shows you how to use ASP.NET Core Diagnostics.


An ASP.NET Core web app requires certain setup before being executed properly. However, the configuration steps are complex and critical settings might be neglected, which leads to failed deployment and miserable issues such as 502.5 and 500.30,

  • ASP.NET Core module is not installed.

  • ASP.NET Core module version does not match the minimal version required by the web apps.

  • Visual C++ 2015 runtime is not installed.

  • Handler setting in web.config is invalid.

  • In-process module has no access to the content folder.

  • Binaries generated for in-process hosting have bitness different from the target application pool.

  • Affected by .NET Core SDK known issues such as this GitHub issue.

A thorough diagnostics tool can reveal typical configuration mistakes and help resolve them.


Minimal ASP.NET Core module version required can be found in articles like this download page.

The Built-in ASP.NET Core Diagnostics

For web sites opened in Jexus Manager, there is an action called ASP.NET Core Diagnostics showed.

A report is generated when “Generate Report” button is clicked.


Typical things analyzed by ASP.NET Core Diagnostics include but not limited to,

  • ASP.NET Core module on IIS.

  • Visual C++ 2015 runtime.

  • Application pool (No Managed Code).

  • Handler in web.config.

  • Web app runtime version.

  • In-process mode bitness.