How can I solve CORS problems in NGINX "The 'Access-Control-Allow-Origin' header contains multiple values '*,*', but only one is allowed."

Question

I'm running tests on a server using NGINX and PHP to run back-end services and I have a CORS problem

I have the following settings in nginx.conf:

#user  nobody;
worker_processes  1;

# error_log  /logs/error.log;


#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    # Format access.log
    log_format main '$remote_addr - $remote_user [$time_local] '
                           '"$request" $status $body_bytes_sent '
                           '"$http_referer" "$http_user_agent" "$gzip_ratio"';

    # Enable logs in access.log
    access_log  logs/access.log  main;

    # Enable error logs global
    error_log  logs/error.log info;
    error_log  logs/error.log notice;
    error_log  logs/error.log warn;
    error_log  logs/error.log error;
    error_log  logs/error.log alert;
    error_log  logs/error.log emerg;


    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;

    server {
        gzip on;
        # Register logs in http
        access_log  logs/access.log  main;
        listen 80;
        server_name  localhost;

        root C:\Users\Administrator\Desktop\proyecto\grownet\backend\public;
        index index.php index.html index.htm;

    add_header X-Frame-Options "SAMEORIGIN";
        add_header X-Content-Type-Options "nosniff";

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            try_files $uri $uri/ /index.php?$query_string;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ \.php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        location ~ \.php$ {
            # CORS in C:\nginx\conf\snippets\cors_config.conf
            include 'snippets/cors_configs.conf';
            fastcgi_pass   127.0.0.1:9123;
            fastcgi_index  index.php;
            fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
            include        fastcgi_params;
        }

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        location ~ /\.ht {
           deny  all;
        }
    }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    #    listen       8000;
    #    listen       somename:8080;
    #    server_name  somename  alias  another.alias;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}


    

}

New changes

And here is the CORS setting

add_header 'Access-Control-Allow-Origin' '$http_origin' always;
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS';
            add_header 'Access-Control-Allow-Headers' 'Content-Type, Authorization, X-Requested-With';

It's not currently located in the 'snippets/cors_configs.conf' file, add the settings within nginx.conf exactly in 'location ~ .php${....}'

Now when running the service, I get new following error:

Access to XMLHttpRequest at 'http://example/api/categories/all' from origin 'http://localhost:3000' has been blocked by CORS >policy:Response to preflight request doesn't pass access control >check: The 'Access-Control-Allow-Origin' header contains multiple >values '*, http://localhost:3000', but only one is allowed.

Now I have a new error, I'm very confused as to why the source of that error. is it some problem on the frontend side or the person testing on my server has old headers that for that reason skipped those errors?

It's important to note that the problem isn't with the php code, since I have the same environment but in Apache server, with CORS configuration enabled so it has no blocks and it's fine. How can I set it up in nginx?

What do I have to do to avoid having multiple Access-Control-Allow-Origin problem?