IIS ASP.NET 6 startup throws System.IO.DirectoryNotFoundException: D:\agent\_work\38\s\IdentityServer\wwwroot\

Question

We are updating one of our applications, in this case IdentityServer, from .NET 5 to .NET 6. It is being hosted by IIS and deployed by Azure Devops Services. The issue we are seeing is that on our development environment the website fails to load but on our staging environment it runs just fine. The error we are seeing on development is

12:45:37.519|Fatal|1||Host terminated unexpectedly.||
System.IO.DirectoryNotFoundException: D:\agent\_work\38\s\IdentityServer\wwwroot\
   at Microsoft.Extensions.FileProviders.PhysicalFileProvider..ctor(String root, ExclusionFilters filters)
   at Microsoft.Extensions.FileProviders.PhysicalFileProvider..ctor(String root)
   at Microsoft.AspNetCore.Hosting.StaticWebAssets.StaticWebAssetsLoader.<>c.<UseStaticWebAssetsCore>b__1_0(String contentRoot)
   at Microsoft.AspNetCore.StaticWebAssets.ManifestStaticWebAssetFileProvider..ctor(StaticWebAssetManifest manifest, Func`2 fileProviderFactory)
   at Microsoft.AspNetCore.Hosting.StaticWebAssets.StaticWebAssetsLoader.UseStaticWebAssetsCore(IWebHostEnvironment environment, Stream manifest)
   at Microsoft.AspNetCore.Hosting.StaticWebAssets.StaticWebAssetsLoader.UseStaticWebAssets(IWebHostEnvironment environment, IConfiguration configuration)
   at Microsoft.AspNetCore.WebHost.<>c.<ConfigureWebDefaults>b__9_0(WebHostBuilderContext ctx, IConfigurationBuilder cb)
   at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass9_0.<ConfigureAppConfiguration>b__0(HostBuilderContext context, IConfigurationBuilder builder)
   at Microsoft.Extensions.Hosting.HostBuilder.BuildAppConfiguration()
   at Microsoft.Extensions.Hosting.HostBuilder.Build()
   at IdentityServer.Program.Main(String[] args) in D:\agent\_work\38\s\IdentityServer\Program.cs:line 23

The path it reports, D:\agent\_work\38\s\IdentityServer\wwwroot\ is interesting because that path is the same as the path from the DevOps build machine. We don't see this error if we revert back to .NET 5 and we don't see the problem on our staging machine.

The Program.cs class is defined as

using System;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using NewRelic.LogEnrichers.Serilog;
using Serilog;
using Serilog.Events;

namespace IdentityServer
{
    public class Program
    {
        public static int Main(string[] args)
        {
            try
            {
                CreateLogger();
                Log.Information("Starting host...");
                CreateHostBuilder(args).Build().Run();
                return 0;
            }
            catch (Exception ex)
            {
                Log.Fatal(ex, "Host terminated unexpectedly.");
                return 1;
            }
            finally
            {
                Log.CloseAndFlush();
            }
        }

        public static void CreateLogger()
        {
            var configuration = GetConfiguration();
            Log.Logger = new LoggerConfiguration()
                .ReadFrom.Configuration(configuration)
                .Enrich.FromLogContext() // allows logging middleware to inject output values
                .Enrich.WithThreadId()
                .Enrich.WithNewRelicLogsInContext()
                .CreateLogger();
        }

        public static IHostBuilder CreateHostBuilder(string[] args)
        {
            var configuration = GetConfiguration();
            return Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(
                    webBuilder =>
                    {
                        webBuilder.UseConfiguration(configuration);
                        webBuilder.UseSerilog();
                        webBuilder.UseIIS();
                        webBuilder.CaptureStartupErrors(true);
                        webBuilder.UseStartup<Startup>();
                    });
        }

        private static IConfiguration GetConfiguration()
        {
            var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
            var builder = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json")
                .AddJsonFile($"appsettings.{environment}.json", true, true);
            var configuration = builder.Build();

            return configuration;
        }
    }
}

We do have other .NET 6 web applications running just fine on this instance of IIS. I was thinking that the problem might be in our release pipelines but they are identical in their task configurations between the environments. Tried looking for the directory path in the code or configuration but don't see it anywhere. Have tried manually setting the WebRoot and ContentRoot paths via .UseWebRoot("path to folder") and .UseContentRoot("path to folder") in the Program.cs but didn't see any change in the logs or the app starting.

Even updated the web.config file to have the exact path for executing the project dll in the aspNetCore element but still no change.

Update 10 Feb 2022

Added debug output to the startup to verify file and folder paths. Everything in the environment variables and execution file path look correct.

ASPNETCORE_IIS_PHYSICAL_PATH - C:\inetpub\webapps\IdentityServer\
Executable Path: C:\inetpub\webapps\IdentityServer\IdentityServer.dll