This is occurring fairly regularly for users of 12.04 as seen on errors.ubuntu.com:
https://errors.ubuntu.com/bucket/?id=/usr/sbin/aptd:KeyError:_inline_callbacks:put -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/936122 Title: Possible race in the transaction limbo (perhaps of run with remove_from_connection_without_exception) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/aptdaemon/+bug/936122/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs