Host ASP.NET Core on Windows with IIS

A recent push to production broke an ASP.NET Core application I have running and it took me a while to find out the underlying problem.

The error was 502 - Web server received an invalid response while acting as a gateway or proxy server with nothing obvious in the logs that helped me.

First I published a last known good version of my application by creating a new branch in git and resetting it to the last known good commit I had.

The idea being I can deploy from this branch while I investigated and once fixed I could delete the branch.

git reset e64c51bf1c3bdde753ff2d8fd8b18d4d902b8b5b --hard

Then digging around the changes between branches in git I noticed that either Visual Studio and/or my MSBuild based deployment script had added a property pointing to hostingModel="InProcess" to my web.config and a property referencing AspNetCoreModuleV2 to my .csproj file.

So with some time spent on both StackOverflow and the ASP.NET Core documentation sites it was apparent that in order to have the more performantInProcess hosting model via the AspNetCoreModuleV2 module the .NET Core 2.2 Runtime & Hosting Bundle for Windows (v2.2.2) needs to be installed.

After many combinations and deployments, I ended up with this successful combination of settings.

Project File

<Project Sdk="Microsoft.NET.Sdk.Web">
    <PackageReference Include="Microsoft.AspNetCore.App" />


    Configure your application settings in appsettings.json. Learn more at
        <rule name="HTTPS rewrite behind ELB rule" stopProcessing="true">
          <match url="^(.*)$" ignoreCase="false" />
            <add input="{HTTP_X_FORWARDED_PROTO}" pattern="^http$" ignoreCase="false" />
          <action type="Redirect" redirectType="Found" url="https://{SERVER_NAME}{URL}" />
      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
    <aspNetCore processPath="dotnet" arguments=".\web.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" forwardWindowsAuthToken="false" hostingModel="InProcess" />

So after the install of .NET Core 2.2 Runtime & Hosting Bundle for Windows (v2.2.2) and one reboot later all was well again. 🙌

Success 🎉