Error 500 when update Drupal modules

February 1, 2015 1.1k views

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?

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