I know I have seen such issue a short time ago from a other user. I will give this a search on launchpad during today.
** Summary changed: - cannot upgrade to v13.04 + cannot upgrade to v13.04 - ERROR openCache() failed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1168307 Title: cannot upgrade to v13.04 - ERROR openCache() failed To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1168307/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs