This problem appears to have been exposed by the update to apt 0.9.12.1 (0.9.12.1)
I have made three changes to the unattended-upgrade script to dig into this: See enclosed patch. 1. Initialized return code to eliminate referenced before assignment in the exception path 2. Added tracback code to see root cause of error in handler I now get the following traceback information, which points me to 726156: Exception: could not convert string to float: amd64Traceback (most recent call last): File "/usr/bin/unattended-upgrade", line 701, in do_install logfile_dpkg, options.verbose or options.debug) File "/usr/bin/unattended-upgrade", line 319, in upgrade_normal res = cache.commit(install_progress=iprogress) File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 504, in commit res = self.install_archives(pm, install_progress) File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 467, in install_archives res = install_progress.run(pm) File "/usr/lib/python2.7/dist-packages/apt/progress/base.py", line 206, in run res = self.wait_child() File "/usr/lib/python2.7/dist-packages/apt/progress/base.py", line 276, in wait_child self.update_interface() File "/usr/bin/unattended-upgrade", line 173, in update_interface apt.progress.base.InstallProgress.update_interface(self) File "/usr/lib/python2.7/dist-packages/apt/progress/base.py", line 253, in update_interface if float(percent) != self.percent or status_str != self.status: ValueError: could not convert string to float: amd64 -- Marty
38d37 < import traceback 682d680 < pkg_install_success = False 705d702 < traceback.print_exc()