I am having the same problem, although I was able to maneuver around it. It appears to affect my /dashboard link, but not (for example) my /cms_page link. So by manually changing the URL I was able to get around that and at least get into the parts of the admin side which don’t use this particular piece of code. Still don’t know how to fix the issue for the pages with this problem, though.
Also worth mentioning is that when I tried to upgrade to 1.2, I got this:
“upgrade ok: channel://connect.magentocommerce.com/core/Lib_Google_Checkout-1.2.0
upgrade ok: channel://connect.magentocommerce.com/core/Lib_Js_Calendar-1.2.0
upgrade ok: channel://connect.magentocommerce.com/core/Lib_Js_Prototype-1.2.0
upgrade ok: channel://connect.magentocommerce.com/core/Lib_ZF_Locale-1.7.2
upgrade ok: channel://connect.magentocommerce.com/core/Lib_Js_Mage-1.2.0
upgrade ok: channel://connect.magentocommerce.com/core/Lib_ZF-1.7.2
permission denied (delete): ./.htaccess
permission denied (delete): ./index.php”
I tried temporarily changing the permissions on .htaccess and index.php to 777, and running the upgrade again, but same result. Now the Magento connect manager page says I still need all of these upgrades (although the messages above seems to indicate that six of them happened successfully). I am guessing that it did upgrade something, but the file currency.php which is mentioned in the error message does not appear to have been touched, so I am not sure what to do about restoring.
This is my first time using the upgrade feature (needless to say it is not going smoothly), so I am not sure what the “Uninstall” feature does. Is this a restore, which will put the old code back? Or does it just remove the new code and assume I have a copy of the old code somewhere to restore it? Any help or advice is appreciated.