"502 Bad Gateway messages" after clicking the "Login as a User" button
If you get a "502 Bad Gateway" message after clicking on the "Login as a User" button, follow the instructions below.
Navigate to the domain settings (Plesk or cPanel), via your hosting provider panel, go to the Apache & Nginx Settings and add the following in the box "Additional Nginx directives".
proxy_buffering on; proxy_buffer_size 128k; proxy_buffers 4 256k; proxy_busy_buffers_size 256k;
or
fastcgi_buffers 16 16k; fastcgi_buffer_size 32k;
This is a known issue on WordPress. If you are unfamiliar with editing the server settings, it's better to ask your hosting provider to do this.