I did an upgrade from Magento CE 1.9.0.1 --> 1.9.1 in my staging environment The frontend is just working fine but the backend gives me the headache. * I can't login. It only shows a white screen and no errors.
I've read that this could be caused by bad themes or plugins. So install it once again in 1.9.0.1 and setup the default/deafult theme and remove all the plugins (set to false in /etc/modules). Did the upgrade once again but sadly with the same result.
I followed the hints on this page: Fundamentals for debugging a Magento store but still no login possible and neither clues or errors.
I've a log-file during the upgrade and all seems well but 2 issues:
Checking dependencies of packages
Package community/Mage_Core_Modules failed: Detected Mage_Core_Modules conflict of versions: 1.9.0.1-1.9.0.1 and 1.9.1.0-1.10.0.0
Installing package community/Mage_All_Latest 1.9.0.1
Package community/Mage_All_Latest 1.9.0.1 installed successfully
Installing package community/Interface_Adminhtml_Default 1.9.0.0
Error:
install: Failed to open file /home/schapenv/public_html/staging/downloader/.cache/community/Interface_Adminhtml_Default-1.9.0.0/app/design/adminhtml/default/default/template/downloadable/sales/order/invoice/create/items/renderer
Installing package community/Interface_Frontend_Default 1.9.0.0
Is this a clue why I can't login?