If you have eXist-db behind a reverse nginx proxy, where you wish to remove the /exist prefix, the links on the Dashboard to eXide etc are incorrect. They always try to access /exist.

For example with a standard eXist-db installation and the following nginx config:

server {
        listen 80 default_server;
        listen [::]:80 default_server;

        server_name _;

        charset utf-8;

        location / {
                proxy_pass http://localhost:8080/exist/;
        }

}

Accessing http://myserver/ will bring up the Dashboard, however clicking "eXide" or similar will 404 as it will try and take you to http://myserver/exist/apps/eXide/index.html