net::ERR_INVALID_HTTP_RESPONSE error after post request with Angular 7

In ASP.NET Core 2.2, we released a new Server which runs inside IIS for Windows scenarios. The issue you are running into looks like: https://github.com/aspnet/AspNetCore/issues/4398.

When sending the XMLHttpRequest, there is a preflight OPTIONS request which returns a status code of 204. This was incorrectly handled by the IIS server, returning an invalid response to the client.

In your ASP.NET Core application, can you please try the workaround for now:

app.Use(async (ctx, next) =>
{
  await next();
  if (ctx.Response.StatusCode == 204)
  {
    ctx.Response.ContentLength = 0;
  }
});

in the beginning of Configure method.

This will also be fixed in the next patch release of ASP.NET Core. I will follow up when the patch is released.

Edit: The latest release (2.2.1) should address this problem: https://dotnet.microsoft.com/download/dotnet-core/2.2. Please try and see if the issue is resolved.

I figured out where the problem is located. It's on the server side. Did you use ASP.NET Core 2.2 ? After downgrading to 2.1, it's finally working !

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" Version="2.1.0"/>
    <PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.1.0" PrivateAssets="All" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="2.1.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.1.0" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.1.0" />
  </ItemGroup>

  <ItemGroup>
    <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="2.0.0" />
  </ItemGroup>
</Project>

But I can't understand why. The only thing that changed is in one header, the Server header. It changed from Microsoft-IIS/10.0 (2.2) to Kestrel (2.1)