i wont be a smart-aleck but it happen to me and everywhere in this forum i can read issus that caused by the same reason.
The reason is that some necessary modules (like Interface_Adminhtml_Default) are not installed.
If you now push update, the “Mage_Core_Modules” will upgrade, but not the absolutly necessary files in /design/adminhtml/ and magento will run into trouble. No wonder, the files are handle by the missing “Interface_Adminhtml_Default” module and both modules have a really strong interdependency.
This can happen if you upload the initial installation by ftp. So the module is not automaticly present. If you use the downloader for initial installation the module is present.
To ensure the integrity of the magento core-modules i will quote Micheal. His hint helped me
In order to prevent this kind of problems please install Mage_All_Latest meta-package.
The extension key to copy-paste is
This meta-package ensures the integrity of Magento core modules. Basically it should be already shown as installed, because it is the package that is installed during download process from magento-downloader.
When upgrading to the next version you will have to select “Upgrade” only for Mage_All_Latest - all other core modules will be upgraded automatically.
Ok, iam a newbie on magento and i am all others as sure about this. But i see.. or feel that this is one of the reasons for many upgrade-issus. If not, so please admin delete this post.
sorry for my bad english syntax. I hope its readable.