ASP.NET Core Web API - Fetch error undefined /swagger/MyApp API v1/swagger.json

Question

I developed ASP.NET Core-5 Web API AND ALSO IMPLEMENTED Swagger in it:

startup.cs:

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddVersioning();
        services.AddSwagger();
        ...
    }


    public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IServiceProvider serviceProvider, IApiVersionDescriptionProvider provider,)
    {
        app.UseDeveloperExceptionPage();
        app.UseStatusCodePagesWithReExecute("/errors/{0}");
        app.UseVersionedSwagger(provider);
    ...
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllerRoute(
               name: "default",
               pattern: "{controller}/{action=Index}/{id?}");
        });
    }

Swagger:

    public static IServiceCollection AddVersioning(this IServiceCollection services)
    {
        services.AddApiVersioning(
            options =>
            {
                options.ReportApiVersions = true;
            });
        services.AddVersionedApiExplorer(
            options =>
            {
                options.GroupNameFormat = "'MyApp API v'VVV";

                options.SubstituteApiVersionInUrl = true;
            });

        return services;
    }


    public static IServiceCollection AddSwagger(this IServiceCollection services)
    {
        services.AddTransient<IConfigureOptions<SwaggerGenOptions>, ConfigureSwaggerOptions>();

        services.AddSwaggerGen(options =>
        {
            options.OperationFilter<SwaggerDefaultValues>();

            options.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
            {
                Scheme = "Bearer",
                Description = @"JWT Authorization header using the Bearer scheme. <br><br> 
                  Enter 'Bearer' [space] and then your token in the text input below.
                  <br><br>Example: 'Bearer 12345abcdef'",
                Name = "Authorization",
                In = ParameterLocation.Header,
                Type = SecuritySchemeType.Http
            });

            options.OperationFilter<SwaggerAuthorizeCheckOperationFilter>();

            // integrate xml comments
            options.IncludeXmlComments(XmlCommentsFilePath);
        });

        return services;
    }


    public static IApplicationBuilder UseVersionedSwagger(this IApplicationBuilder app, IApiVersionDescriptionProvider provider)
    {
        app.UseSwagger();

        app.UseSwaggerUI(
            options =>
            {
                // build a swagger endpoint for each discovered API version
                foreach (var description in provider.ApiVersionDescriptions)
                {
                    options.SwaggerEndpoint($"/swagger/{description.GroupName}/swagger.json", description.GroupName.ToUpperInvariant());
                }
            });

        return app;
    }

Everything worked fine on the local system, but when I deployed to IIS on the Remote server.

Then I tried to test:

https://localhost:8443/myapp/

gives:

No webpage was found for the web address: https://localhost:8443/myapp/

while

https://localhost:8443/myapp/swagger/index.html

gives:

I got this error:

Fetch error undefined /swagger/MyApp API v1/swagger.json

How do I resolve this?

Thanks

Answer 1

Try to add the following code in the Configure method in the startup.cs file:

if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
        app.UseSwagger(c =>
        {
            c.RouteTemplate = "/swagger/{documentName}/swagger.json";
        });
        app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "API v1"));
    }

Then add the following code in the ConfigureServices method：

services.AddSwaggerGen(c =>
    {
        c.SwaggerDoc("v1", new OpenApiInfo { Title = "API", Version = "v1" });
        c.ResolveConflictingActions(apiDescriptions => apiDescriptions.First());
    });

RouteTemplate is used here, the difference between it and the SwaggerEndpoint string. One uses {documentName} and the other uses "v1" as the text.

Specific reference documents:

https://www.thecodebuzz.com/resolved-failed-to-load-api-definition-undefined-swagger-v1-swagger-json/