Asp.NET Core 3.1 and Swashbuckle.AspNetCore.Swagger

Question

I updated my asp.net core app to v3.1 and updated my Swagger form v5.04 rc to v5.0, and everything stopped to work. The API is working, but I can't generate swagger file, and I was able.

Here is my swagger configuration.

public static class SwaggerConfig
    {
        [Obsolete]
        public static void ConfigureSWAGGER(this IServiceCollection serviceColletion)
        {
            if (serviceColletion == null)
            {
                throw new ArgumentNullException(nameof(serviceColletion));
            }

            // Use http://localhost:5000/swagger/ui/index to inspect API docs
            serviceColletion.AddSwaggerGen(x =>
            {
                x.SwaggerDoc(Constatns.BackofficeSwaggerGroup, new OpenApiInfo { Title = "Portal Nekretnine - Backoffice", Version = Constatns.BackofficeSwaggerGroup });
                x.SwaggerDoc(Constatns.PublicSwaggerGroup, new OpenApiInfo { Title = "Portal Nekretnine - Public", Version = Constatns.PublicSwaggerGroup });

                // This code allow you to use XML-comments
                string xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
                string xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
                if (File.Exists(xmlPath))
                {
                    x.IncludeXmlComments(xmlPath);
                }

                x.AddSecurityDefinition
                (
                    "Bearer",
                    new OpenApiSecurityScheme
                    {
                        In = ParameterLocation.Header,
                        Description = "Please enter token into the field",
                        Name = "Authorization",
                        Type = SecuritySchemeType.ApiKey
                    }
                );
            });
        }

        public static void UseSWAGGER(this IApplicationBuilder applicationBuilder)
        {
            // Enable middleware to serve generated Swagger as a JSON endpoint.
            applicationBuilder.UseSwagger();

            // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
            // specifying the Swagger JSON endpoint.
            applicationBuilder.UseSwaggerUI(x =>
            {
                x.SwaggerEndpoint($"/swagger/{Constatns.BackofficeSwaggerGroup}/swagger.json", "Portal Nekretnine - Backoffice");
                x.SwaggerEndpoint($"/swagger/{Constatns.PublicSwaggerGroup}/swagger.json", "Portal Nekretnine - Public");
            });
        }
    }

And this is my startup.cs

public partial class Startup
    {
        public IConfiguration Configuration { get; }

        public Startup(IConfiguration configuration, IWebHostEnvironment env)
        {
            Configuration = configuration;

            if (env.IsDevelopment())
            {
                IConfigurationBuilder builder = new ConfigurationBuilder()
                                                                        .SetBasePath(env.ContentRootPath)
                                                                        .AddJsonFile($"appsettings.development.json", optional: true)
                                                                        .AddEnvironmentVariables();

                Configuration = builder.Build();
            }
            else
            {
                IConfigurationBuilder builder = new ConfigurationBuilder()
                                                                        .AddJsonFile($"appsettings.production.json", optional: true)
                                                                        .AddEnvironmentVariables();

                Configuration = builder.Build();
            }
        }

        // This method gets called by the runtime. Use this method to add services to the container.
        [System.Obsolete]
        public void ConfigureServices(IServiceCollection services)
        {
            SetServices(services);

            services.ConfigureCOMPRESSION();

            //disable built in model validator
            services.Configure<ApiBehaviorOptions>(options =>
            {
                options.SuppressModelStateInvalidFilter = true;
            });

            services.AddMvcCore(options =>
                            {
                                //Validate model
                                options.Filters.Add(typeof(ValidateModelAttribute));

                                // Add "Cache-Control" header
                                options.Filters.Add(typeof(CacheControlFilter));

                                // Add custom binder provider for mapping json object form multipart/form-data
                                options.ModelBinderProviders.Insert(0, new JsonModelBinderProvider());
                            })
                            .SetCompatibilityVersion(CompatibilityVersion.Version_3_0)
                            .AddApiExplorer();

            services.AddControllers()
                            .AddNewtonsoftJson(options =>
                            {
                                options.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver();
                                options.SerializerSettings.Converters.Add(new JsonDateConverter());
                                options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
                                options.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;
#if DEBUG
                                options.SerializerSettings.Formatting = Formatting.Indented;
#else
                                options.SerializerSettings.Formatting = Formatting.None;
#endif
                            });

            services.Configure<ForwardedHeadersOptions>(options =>
            {
                options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
            });

            services.ConfigureCookieAuthentication();
            services.ConfigureAUTH(Configuration);

            services.ConfigureCORS();

            services.ConfigureSWAGGER();
            services.AddSwaggerGenNewtonsoftSupport(); // explicit opt-in - needs to be placed after AddSwaggerGen()
        }

        // 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
            {
                app.UseHsts();
            }

            app.UseRouting();

            app.UseCOMPRESSION();

            app.UseAUTH();
            app.UseAuthorization();

            app.UseCORS();
            app.UseSWAGGER();

            app.UseHttpStatusCodeExceptionMiddleware();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }

and an example of my controllers:

[ApiController]
public class SecurityController : ControllerBase
{

        [ApiExplorerSettings(GroupName = Constatns.PublicSwaggerGroup)]
        [SwaggerOperation(OperationId = "registerVisitor")]
        [HttpPost("api/register/visitor")]
        [ValidateModel]
        [AllowAnonymous]
        [ProducesResponseType((int)HttpResponseType.OK, Type = typeof(TokenResponse))]
        [ProducesResponseType((int)HttpResponseType.BadRequest)]
        [Produces("application/json")]
        public async Task<TokenResponse> RegisterVisitor([FromBody] RegisterVisitorRequest data)
        {}
}

The error that I am getting are:

fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1] An unhandled exception has occurred while executing the request. System.MissingMethodException: Method not found: 'Void Microsoft.OpenApi.Writers.OpenApiJsonWriter..ctor(System.IO.TextWriter)'. at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.RespondWithSwaggerJson(HttpResponse response, OpenApiDocument swagger) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.RespondWithSwaggerJson(HttpResponse response, OpenApiDocument swagger) at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider) at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)

thnx

Solution

After hours and hours digging I found that with Microsoft.OpenApi 1.2.0-preview isn't compactibile with .net core 3.1 and swagger v5, use v1.1.4 of Microsoft OpenApi