5.0.0 - SerializeAsV2 - Invalid URI: The format of the URI could not be determined.

[danburgener]

When I upgraded to use version 5.0.0 and use SerializeAsV2, I get an error saying "Invalid URI: The format of the URI could not be determined." If I don't use SerializeAsV2, I don't get the error. Unfortunately, I need to use SerializeAsV2. How can I fix this? Also, this only occurs when using IIS, not IISExpress.

1. Include package:
   <PackageReference Include="Swashbuckle.AspNetCore" Version="5.0.0" />

2. Set swagger to use v2

applicationBuilder.UseSwagger(c => c.SerializeAsV2 = true)
                    .UseSwaggerUI(c =>
                    {
                        c.SwaggerEndpoint($"{pathPrefix}/swagger/{applicationVersion}/swagger.json", $"{applicationName} {applicationVersion}");
                    });

3. Try to get json from url, will result in the following error

{
"Message": "Internal Server Error.",
"StackTrace": "   at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind)\r\n   at System.Uri..ctor(String uriString)\r\n   at Microsoft.OpenApi.Models.OpenApiDocument.WriteHostInfoV2(IOpenApiWriter writer, IList`1 servers)\r\n   at Microsoft.OpenApi.Models.OpenApiDocument.SerializeAsV2(IOpenApiWriter writer)\r\n   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.RespondWithSwaggerJson(HttpResponse response, OpenApiDocument swagger)\r\n   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)\r\n   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)\r\n   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)\r\n   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)",
"ErrorMessage": "Invalid URI: The format of the URI could not be determined.",
}

[danburgener]

I was able to get it working by adding PreSerializeFilters. Is this the preferred way?

.UseSwagger(c =>
  {
    c.SerializeAsV2 = true;
    c.PreSerializeFilters.Add((swaggerDoc, httpReq) =>
    {
      swaggerDoc.Servers = new List<OpenApiServer> { new OpenApiServer { Url = $"{httpReq.Scheme}://{httpReq.Host.Value}{pathPrefix}" } };
    });
  })

[domaindrivendev]

Dup of #1495