If you’re experiencing issues during logging in in and you get stuck on message ‘Sending user info, please wait…‘ there might be couple of issues:

  1. Most common cause of this problem are cache plugins active on your site. Try to disable them to see if that help. If it does, you might need to change some settings in those plugins as they might have to aggressive optimization for this feature to work.
  2. Another but less common reasonis often related to custom mod_security rules. Some hosting providers block login requests from non standard paths, so try to contact your hosting provider and ask them about it.
  3. And last but not least, you may experience this issue on nginx server, in that case, add the following lines to /etc/nginx/nginx.com 
    fastcgi_temp_file_write_size 10m; 
fastcgi_busy_buffers_size 512k; 
fastcgi_buffer_size 512k;
fastcgi_buffers 16 512k;
client_max_body_size 50m; 
proxy_buffer_size 16k; 
proxy_busy_buffers_size 16k;

    if that won’t help, check if you have Nginx Content caching enabled, you might need to disable that to fix that problem