Unable to start Kestrel, system.InvalidOperationException

Question

I'm having problem starting my web api. I am using .net core 3.0 Web Api. I was debugging and testing it locally using iis express without problems. but when I tried to deploy the web api to my linux server I get error messages that look like this:

crit: Microsoft.AspNetCore.Server.Kestrel[0] Unable to start Kestrel. System.InvalidOperationException: A path base can only be configured using IApplicationBuilder.UsePathBase().

and running it on my local machine in debug mode does the same thing. so I created a new profile to start the executable when I debug the application in VS.

Exception thrown: 'System.InvalidOperationException' in System.Private.CoreLib.dll An unhandled exception of type 'System.InvalidOperationException' occurred in System.Private.CoreLib.dll A path base can only be configured using IApplicationBuilder.UsePathBase().

here's the code in Program.cs and Startup.cs

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .ConfigureKestrel((a, b) => { })
                .UseUrls("http://*:5050,https://*:5051")
                .UseKestrel()                
                .UseStartup<Startup>();
}

public class Startup

{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc(options => options.EnableEndpointRouting = false).SetCompatibilityVersion(CompatibilityVersion.Version_3_0);

        connectionObject.SetConfiguration(Configuration);

        // configure strongly typed settings objects
        var appSettingsSection = Configuration.GetSection("AppSettings");
        services.Configure<AppSettings>(appSettingsSection);

        // configure jwt authentication
        var appSettings = appSettingsSection.Get<AppSettings>();
        var key = Encoding.ASCII.GetBytes(appSettings.Secret);
        services.AddAuthentication(x =>
        {
            x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
            x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        })
        .AddJwtBearer(x =>
        {
            x.Events = new JwtBearerEvents
            {
                OnTokenValidated = context =>
                {
                    var userService = context.HttpContext.RequestServices.GetRequiredService<IUserData>();
                    var userId = int.Parse(context.Principal.Identity.Name);
                    var user = userService.GetById(userId);
                    if (user == null)
                    {
                        // return unauthorized if user no longer exists
                        context.Fail("Unauthorized");
                    }
                    return Task.CompletedTask;
                }
            };
            x.RequireHttpsMetadata = false;
            x.SaveToken = true;
            x.TokenValidationParameters = new TokenValidationParameters
            {
                ValidateIssuerSigningKey = true,
                IssuerSigningKey = new SymmetricSecurityKey(key),
                ValidateIssuer = false,
                ValidateAudience = false
            };
        });

        // configure DI for application services
        services.AddScoped<IUserData, UD>();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {

        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseAuthentication();
        app.UseMvc();
    }
}

here's my launchsettings

{
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:60850",
      "sslPort": 44372
    }
  },
  "$schema": "http://json.schemastore.org/launchsettings.json",
  "profiles": {
    "IIS Express": {
      "commandName": "Executable",
      "launchBrowser": true,
      "launchUrl": "api/values",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "Kestrel": {
      "commandName": "Executable",
      "executablePath": ".\\WebApi.exe",
      "applicationUrl": "http://localhost:5050"
    }
  }
}

I tried fiddling with

app.UsePathBase("/"); 

or

app.UsePathBase("http://localhost:5050") 

but in the latter case the error message is the value needs to start with /

I have seen other complaining about this issue before, but their solutions did not work for me. why am I getting this at all?

Answer 1

The UseUrls(...) method expects the URL's to be separated by a semi-colon ;, not a comma ,.

Try changing the line in program.cs to

.UseUrls("http://*:5050;https://*:5051")

The documentation says (emphasis mine):

The value provided using these approaches can be one or more HTTP and HTTPS endpoints (HTTPS if a default cert is available). Configure the value as a semicolon-separated list (for example, "Urls": "http://localhost:8000;http://localhost:8001").

You can see the complete documentation here