нету доступа in wp-admin к update and plugins.

Попытался проапдейтить wordpress8 на 9.1 в http://blog.site.com/wp-admin/update-core.php

получаю:

Connection closed by remote server
You tried to access the address http://blog.site.com/wp-admin/update-core.php, which is currently unavailable. Please make sure that the web address (URL) is correctly spelled and punctuated, then try reloading the page.

в логах apache:

Jun 17 17:23:43 logger: [Tue Jun 17 17:23:43 2014] [notice] child pid 17029 exit signal Segmentation fault (11)
Jun 17 17:23:44 logger: [Tue Jun 17 17:23:44 2014] [notice] child pid 17027 exit signal Segmentation fault (11)
Jun 17 17:23:44 logger: [Tue Jun 17 17:23:44 2014] [notice] child pid 17909 exit signal Segmentation fault (11)
Jun 17 17:23:45 logger: [Tue Jun 17 17:23:45 2014] [notice] child pid 17898 exit signal Segmentation fault (11)
Jun 17 17:23:46 logger: [Tue Jun 17 17:23:46 2014] [notice] child pid 15732 exit signal Segmentation fault (11)

Тоже самое при обращении к плагинам. Все остальное работает без проблем.
Как можно продиагностировать проблему на более низком уровне?