.NET Core publish to IIS - HTTP Error 502.3 - Bad Gateway - The specified CGI application encountered an error and the server terminated the process

Question

I'm trying to publish to IIS a .NET Core ASP.NET Website I upgraded from RC2 to RTM.

As a sanity check, I was successfully able to publish the template/sample "ASP.NET Core Web Application (.NET Framework)" app from Visual Studio 2015.

But for some reason, when publishing the RTM upgraded app, I'm getting HTTP Error 502.3 - Bad Gateway The specified CGI application encountered an error and the server terminated the process.

The site DOES work running IIS Express from Visual Studio.

How can I debug this? Anyone have any ideas?

web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>

<system.webServer>
    <handlers>
      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified"/>
    </handlers>
    <aspNetCore processPath=".\MyApp.exe" arguments="%LAUNCHER_ARGS%" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
  </system.webServer>
</configuration>

project.json

{
  "buildOptions": {
  "emitEntryPoint": true,
  "preserveCompilationContext": true,
  "warningsAsErrors": true
},
"dependencies": {
  "Microsoft.AspNetCore.Diagnostics.Elm": "0.1.0",
  "Microsoft.AspNetCore.Authentication.Cookies": "1.0.0",
  "Microsoft.AspNetCore.Authorization": "1.0.0",
  "Microsoft.AspNetCore.Diagnostics": "1.0.0",
  "Microsoft.AspNetCore.Hosting": "1.0.0",
  "Microsoft.AspNetCore.Hosting.Abstractions": "1.0.0",
  "Microsoft.AspNetCore.Http.Extensions": "1.0.0",
  "Microsoft.AspNetCore.Localization": "1.0.0",
  "Microsoft.AspNetCore.Mvc": "1.0.0",
  "Microsoft.AspNetCore.Routing": "1.0.0",
  "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
  "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
  "Microsoft.AspNetCore.Session": "1.0.0",
  "Microsoft.AspNetCore.StaticFiles": "1.0.0",
  "Microsoft.Extensions.Caching.SqlServer": "1.0.0",
  "Microsoft.Extensions.Logging.Console": "1.0.0",
  "Microsoft.Extensions.Logging.Debug": "1.0.0",
  "Microsoft.VisualStudio.Web.BrowserLink.Loader": "14.0.0",

  "Microsoft.AspNetCore.Razor.Tools": {
    "version": "1.0.0-preview2-final",
    "type": "build"
  },

  "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
  "Microsoft.Extensions.Configuration.Json": "1.0.0",
  "Microsoft.Extensions.Logging": "1.0.0",
  "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0"
},

"frameworks": {
   "net461": {}
 },

"tools": {
  "BundlerMinifier.Core": "2.0.238",
  "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview2-final",
  "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
},

"scripts": {
  "prepublish": [ "bower install", "dotnet bundle" ],
  "postpublish": "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%"
},

"publishOptions": {
  "include": [
    "wwwroot",
    "web.config",
    "appsettings.json",
    "**/*.cshtml",
    "Config/*.json"
    ]
  ]
 }
}

Answer 1

How can I debug this? Anyone have any ideas?

Here are three ideas:

1. Read this and make sure that you have covered all that it says.

2. Run the published .\MyApp.exe from the command line. Does that work?

   • If it does, you know you have an IIS integration problem.
   • If it does not, you know you have an application problem.

3. Change stdoutLogEnabled="false" to true and then check the logs at stdoutLogFile=".\logs\stdout". The error(s) there might tell you something.

4. Check your IIS Application logs in the Event Viewer. The error(s) there might tell you something.

Event Viewer Application Logs

Answer 2

If you run a task for a long time, and web browser don't receives response in 2 mins(the default request time), you'll get this error. Because after the timeout, IIS will replaces the application to respond to the client with 'Bad Gateway'.

Maybe you should change the request time in the web.config.

Set requestTimeout attribute in section system.webServer / aspNetCore to specifies the duration for which the ASP.NET Core Module will wait for a response from the process listening on %ASPNETCORE_PORT%.

• The requestTimeout must be specified in whole minutes only, otherwise it defaults to 2 minutes.

Just like this:

<system.webServer>
  <aspNetCore requestTimeout="00:20:00" ... />
</system.webServer>

Answer 3

The solutions did not work for me, but what did is:

Enable web developer mode (press F12 in your browser)=> application tab =>then remove all cookies. Refresh the page and voilà: it works. Also you can copy your URL and paste to another browser you haven't run any MVC project.

My project worked on Internet Explorer and Microsoft Edge without any change. Perhaps that's the cause of your error.

Answer 4

Not directly an answer to the OP's specific instance of this 502.3 error, but it also can occur if there is an infinite loop, as I accidentally left in my application:

public class Category
{
    public Category()
    {
        ParentCategory = new Category();
    }

    Category ParentCategory { get; set; }
}

There was no clear error indicating that this was the issue. Hope it helps someone.

Answer 5

One possible cause is, there is some exception after the return statement from your API. In my case, there was a circular reference in the object that I was returning in an IActionResult. While debugging, I converted the object being returned into JSON format, using Newtonsoft.Json.JsonConvert.SerializeObject(). This resulted in following exception being returned from the API endpoint:

Newtonsoft.Json.JsonSerializationException: Self referencing loop detected for property 'xxx' with type 'xxx'. Path 'xxx'.? at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference(JsonWriter writer, Object value, JsonProperty property, JsonContract contract, JsonContainerContract containerContract, JsonProperty containerProperty)