Internal server error on admin/modules/list/confirm I have recently decided to move one of the sites to another hosting provider, and now started to receive this 500 error when submitting changes to admin/modules. The new hosting has different environment where all sites might have their core and contributed modules connected to the central repository; now, in admin/modules all 850 local repository modules can be seen as they were in sites/all/modules. In server logs this error reflect as:


  mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 87437 bytes) in /opt/drupal7/includes/cache.inc on line 463, referer: admin/modules
  
  mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 71 bytes) in /opt/drupal7/includes/form.inc on line 1820
  
  mod_fcgid: stderr: PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 8208 bytes) in /opt/drupal7/modules/field/field.crud.inc on line 711, referer: admin/modules?render=overlay
  
  mod_fcgid: stderr: PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 32 bytes) in /opt/drupal7/includes/file.inc on line 200, referer: admin/modules


The site has a 128 MB memory limit; it is more than on previous hosting, but now some of the enabled modules (like OpenLayers) sometime also issue memory errors (like those above, but on site they work without any 500 errors). 

What can be the reason of this errors? Is there any additional information that can help find what to fix?
You need to check your PHP memory limit on php.ini.
If you use Linux, go to /etc/php.ini to find it out.