Access-Control-Allow-Origin' header contains multiple values 'http://localhost:4200, *', but only one is allowed

Question

I use angular on the front end and .net5 on te backend. I deploy my backend to ubuntu 20.04 server and run it with nginx. I faced this issue while attempt to login. My get functions works well but login(post) is not. I searched hours and hours and add add_header Access-Control-Allow-Origin *; to my etc/nginx/sites-available/default file. But nothing changes. Do you have any idea?

Answer 1

Does your .NET backend allows CORS e.g have a look at https://docs.microsoft.com/en-us/aspnet/core/security/cors?view=aspnetcore-6.0

Also while you are modifying NGINX conf make sure to restart the service. e.g sudo systemctl restart nginx