Rule works but produced "err_empty_response" error when I want to edit it
Have you tried this on multiple servers as well? It is likely something on the server, so other browsers and computer won't make the difference. You did not specify the Drupal version but I ran into a similar situation with Drupal 8 while editing Views.

For me the solution was to increase the PHP memory limit. The linked page shows several ways to do this, but I chose to do it in the php.ini file. I believe it is 256M now.