ASP.NET Core 3.1 CORS error in VS for Mac

Question

Initially, I started to develop my project on PC and now I'm trying to run it on Mac. When my front end tries to reach my web API endpoint, I'm getting the following error:

Failed to load resource: Origin https://localhost:3000 is not allowed by Access-Control-Allow-Origin

The thing is that it works perfectly on Windows, but doesn't work on Mac.

My code to enable CORS:

builder.UseCors(x => x
                .WithOrigins(new string[] { "https://localhost:3000" })
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials());

How to solve this issue?

Serge · Answer 1 · 2020-12-17T17:22:15.350

0

In "ConfigureServices" of your startup.cs add this (it is a different syntax from yours):

 services.AddCors(o => o.AddPolicy("AllowSpecificOrigins", builder =>
            {
                builder..WithOrigins("https://localhost:3000")
                       .AllowAnyMethod()
                       .AllowAnyHeader();
            }));

In "Config" change yours to this:

  app.UseCors("AllowSpecificOrigins");

and place it after UseRouting but before UseAuthorization.

Also remove all Cors attributes from all controller actions.

edited Dec 17 '20 at 17:22

answered Dec 17 '20 at 16:47

Serge

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is it really necessary to "remove all Cors attributes from all controller actions."? – genuinefafa Apr 28 '22 at 13:25
@genuinefafa Usually it works but I guess it depends on the your case, maybe you really need several cors policies – Serge Apr 28 '22 at 14:07

score 0 · Accepted Answer · answered Dec 18 '20 at 06:42

Okay, it turned out that I had to "trust" the dev certificate created by dotnet core command. I opened my backend URL from browser (https://localhost:44372), clicked "Proceed" when the "site is unsafe" prompt appeared and only after that my front end (https://localhost:3000) was able to reach it.

ASP.NET Core 3.1 CORS error in VS for Mac

2 Answers2