SignalR in ASP.NET Core behind Nginx

I was able to solve this by using $http_connection instead of keep-alive or upgrade

server {
  server_name example.com;

  location / {
    proxy_pass http://localhost:5000;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $http_connection;
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
  }
}

I did this because SignalR was also trying to use POST and GET requests to my hubs, so doing just an Upgrade to the connection in a separate server configuration wasn’t enough.