Can't Read Config Values

Question

I have a Magento development environment setup on a virtual box server with a git repo in the root web directory. I've been using this setup for almost a year. Yesterday I checked out master and now if I go to the home page I get a blank white page (view source shows nothing is returned). No errors are in var/log or var/report. I've cleared var/cache and verified my permissions pare properly set. The same branch is checked out on our live site and QA, and both work just fine.

If I go to a product page, the bulk of the page is there, but lots of CSS and JS is missing. I have found that it's trying to load http://example.com/mage/translate.js instead of http://example.com/js/mage/translate.js. So it appears that the config value for the js folder isn't being loaded.

If I go to the admin the login page loads the inputs and dies with this error

Warning: include(Mage/Captcha/Model.php): failed to open stream: No such file or directory

This is caused by these lines

$type = $this->getConfigNode('type');
$this->_captcha[$formId] = Mage::getModel('captcha/' . $type, array('formId' => $formId));

in Mage_Captcha_Helper_Data (lines 71 & 72). The issue is that $type is coming back as null when it should get the default from the Captcha config.xml. I've checked that the config file is there and its loaded by Varien_Simplexml_Config::loadFile().

Can anyone offer any suggestions as to what I may have done to my server to mess it up this badly?

Answer 1

It turns out that it was my own fault the whole time.

Before the blank white page started occurring, I was working on updating a config value in an install script using Mage::getModel('core/config')->saveConfig($path, $value) I accidentally ran that line of code once with $path = ''. This saved a row in core_config_data with a blank path. When I finally noticed that row I deleted it from the database and everything is running fine now.

I haven't found the code to verify this, but I assume what happens is after all the config.xml files are read, Magento pulls down all the rows in core_config_data and tries to insert each row's value in the corresponding path of the xml. When it got to the blank path it removed all the nodes beneath config/default and caused everything to fail.

Hope this helps someone in the future.