I've also had this error and have reported it here: https://bugs.launchpad.net/ubuntu/+source/synaptic/+bug/304792 which seems to be a duplicate of this bug. Running kubuntu jaunty beta with both synaptic and kpackagekit installed. Restarting synaptic seems to fix the issue for me.
-- The package cache file is corrupted, _cache->open()failed https://bugs.launchpad.net/bugs/185215 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
