How can I debug an 'Unknown error' message that I get with every request in Craft? Logging says:
******************************************************************************************************
2015/01/16 14:03:36 [error] [exception.Craft\HttpException.503] exception 'Craft\HttpException' in /storage/www/imagecenter/acceptance/craft/app/etc/web/WebApp.php:873
Stack trace:
#0 /storage/www/imagecenter/acceptance/craft/app/etc/web/WebApp.php(218): Craft\WebApp->_processUpdateLogic()
#1 /storage/www/imagecenter/acceptance/craft/app/framework/base/CApplication.php(180): Craft\WebApp->processRequest()
#2 /storage/www/imagecenter/acceptance/craft/app/index.php(62): CApplication->run()
#3 /storage/www/imagecenter/acceptance/htdocs/index.php(16): require_once('/storage/www/im...')
#4 {main}
REQUEST_URI=/index.php?p=admin/actions/users/getAuthTimeout&dontExtendSession=1
HTTP_REFERER=http://acceptance.imagecenter.blinkdev.nl/index.php?p=admin/entries
---
2015/01/16 14:03:36 [error] [application]
******************************************************************************************************