Error 500 when update Drupal modules
Recently I've transferred several Drupal sites to DigitalOcean droplet (Ubuntu).
Almost all work well.
But when I try to downloading updates for modules I get error:
An AJAX HTTP error occurred. HTTP Result Code: 500 Debugging information follows. Path: /batch?render=overlay&id=82&op=do StatusText: Internal Server Error ResponseText:
I see the error for every Drupal sites at droplet.
I can successfully update modules by drush.
But I want to understand problem.
There is no error record at error.log (Apache)
And there is following line at access.log:
POST /batch?render=overlay&id=83&op=do HTTP/1.1" 500
How can I solve the problem?
What open ports are Drupal need for correct work?