Alright, let's break this down step by step. Your app runs perfectly via dotnet dllname, and IIS's reverse proxy can reach it when it's manually started—so the app itself and IIS proxy config are solid. The root issue is clearly the AspNetCoreModuleV2 failing to initialize your app within IIS, specifically in the in-process hosting mode you're using. Here are targeted fixes and checks:

1. First: Test Out-of-Process Hosting Mode #

Since you haven't tried this yet, it's the fastest way to rule out in-process-specific issues:

• Update your web.config to switch to out-of-process mode, and use a relative path for your DLL (absolute paths can cause permission/resolution bugs in IIS):

  <aspNetCore 
    processPath="dotnet" 
    arguments=".\ESTemplateCompData.dll" 
    stdoutLogEnabled="true" 
    stdoutLogFile=".\logs\stdout" 
    hostingModel="outofprocess" >
    <handlerSettings>
      <handlerSetting name="debugFile" value=".\logs\aspnetcore-debug.log" />
      <handlerSetting name="debugLevel" value="FILE,TRACE" />
    </handlerSettings>
  </aspNetCore>
  

• Make sure the logs folder exists in your app root (c:\escompdata2\logs) and your app pool's admin account has write permissions to it (right-click the folder → Properties → Security → Add your app pool account, grant Modify/Write access).
• Restart your IIS site and app pool, then try accessing the site. If this works, the problem is isolated to in-process hosting mode.

2. Fix In-Process Mode Configuration Issues #

If out-of-process works, focus on these in-process-specific checks:

• Set App Pool to "No Managed Code":
  Open IIS Manager → Your App Pool → Advanced Settings → .NET CLR Version. Select No Managed Code. In-process mode uses AspNetCoreModuleV2 to host the app directly, so IIS's managed code runtime isn't needed—setting this wrong blocks the module from starting.
• Verify AspNetCoreModuleV2 is Installed Correctly:
  Open %windir%\system32\inetsrv\config\applicationHost.config and check for these entries:

  <globalModules>
    <add name="AspNetCoreModuleV2" image="%ProgramFiles%\IIS\Asp.Net Core Module\V2\aspnetcorev2.dll" />
  </globalModules>
  <modules>
    <add name="AspNetCoreModuleV2" lockItem="true" />
  </modules>
  

  If they're missing, reinstall the .NET Hosting Bundle matching your app's .NET version (this installs and registers the module properly).
• Double-Check App Pool Permissions:
  Even with an admin account, in-process mode requires the app pool account to access the .NET runtime directory and all app files:
  • Grant read access to c:\Program Files\dotnet\ for your app pool account
  • Enable permission inheritance on your app root (c:\escompdata2): Right-click → Properties → Security → Advanced → Check "Replace all child object permission entries with inheritable permission entries from this object"

3. Dig Into Hidden Logs #

You mentioned enhanced tracing didn't work—likely a path or permission issue:

• Use absolute paths for log files to avoid ambiguity, e.g., stdoutLogFile="c:\escompdata2\logs\stdout" and debugFile="c:\escompdata2\logs\aspnetcore-debug.log"
• Check the Windows Event Viewer: Go to Windows Logs → Application, and look for events from ASP.NET Core or IIS AspNetCoreModuleV2. These events often have specific error details (like missing runtime files, permission denied, or version mismatches) that don't show up in IIS logs.

4. Fix Absolute Path Problems #

Your current arguments uses an absolute path to the DLL (c:\escompdata2\ESTemplateCompData.dll). In in-process mode, IIS resolves paths relative to the app's physical root—switch to a relative path (.\ESTemplateCompData.dll) and confirm your app pool's Physical Path is set correctly to c:\escompdata2.

If all else fails:

• Uninstall and reinstall the .NET Hosting Bundle for your app's framework version
• Reset IIS completely: Open an admin command prompt and run iisreset /stop, then iisreset /start

内容的提问来源于stack exchange，提问作者Marc-Arthur