apt - update-manager fails with "ImportError: No module named 'ros_buildfarm'" - Ask Ubuntu

when trying update ubuntu 16.04 got error :

sos@sos:~$ sudo update-manager  /usr/bin/update-manager:28: pygiwarning: gtk imported without specifying version first. use gi.require_version('gtk', '3.0') before import ensure right version gets loaded.   gi.repository import gtk /usr/lib/python3/dist-packages/updatemanager/unitysupport.py:29: pygiwarning: dbusmenu imported without specifying version first. use gi.require_version('dbusmenu', '0.4') before import ensure right version gets loaded.   gi.repository import dbusmenu, unity /usr/lib/python3/dist-packages/updatemanager/unitysupport.py:29: pygiwarning: unity imported without specifying version first. use gi.require_version('unity', '7.0') before import ensure right version gets loaded.   gi.repository import dbusmenu, unity traceback (most recent call last):   file "/usr/bin/apt.py", line 21, in <module>     ros_buildfarm.wrapper.apt import main importerror: no module named 'ros_buildfarm'  during handling of above exception, exception occurred:  traceback (most recent call last):   file "/usr/bin/update-manager", line 38, in <module>     updatemanager.updatemanager import updatemanager   file "/usr/lib/python3/dist-packages/updatemanager/updatemanager.py", line 57, in <module>     .metareleasegobject import metarelease   file "/usr/lib/python3/dist-packages/updatemanager/metareleasegobject.py", line 25, in <module>     .core.metarelease import metareleasecore   file "/usr/lib/python3/dist-packages/updatemanager/core/metarelease.py", line 25, in <module>     import apt   file "/usr/bin/apt.py", line 25, in <module>     ros_buildfarm.wrapper.apt import main importerror: no module named 'ros_buildfarm' error in sys.excepthook: traceback (most recent call last):   file "/usr/bin/apt.py", line 21, in <module>    ros_buildfarm.wrapper.apt import main importerror: no module named 'ros_buildfarm'  during handling of above exception, exception occurred:  traceback (most recent call last):   file "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook     apport.fileutils import likely_packaged, get_recent_crashes   file "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>     apport.report import report   file "/usr/lib/python3/dist-packages/apport/report.py", line 30, in <module>     import apport.fileutils   file "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in <module>     apport.packaging_impl import impl packaging   file "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 23, in <module>     import apt   file "/usr/bin/apt.py", line 25, in <module>     ros_buildfarm.wrapper.apt import main importerror: no module named 'ros_buildfarm'  original exception was: traceback (most recent call last):   file "/usr/bin/apt.py", line 21, in <module>     ros_buildfarm.wrapper.apt import main importerror: no module named 'ros_buildfarm'  during handling of above exception, exception occurred:  traceback (most recent call last):   file "/usr/bin/update-manager", line 38, in <module>     updatemanager.updatemanager import updatemanager   file "/usr/lib/python3/dist-packages/updatemanager/updatemanager.py", line 57, in <module>     .metareleasegobject import metarelease   file "/usr/lib/python3/dist-packages/updatemanager/metareleasegobject.py", line 25, in <module>     .core.metarelease import metareleasecore   file "/usr/lib/python3/dist-packages/updatemanager/core/metarelease.py", line 25, in <module>     import apt   file "/usr/bin/apt.py", line 25, in <module>     ros_buildfarm.wrapper.apt import main importerror: no module named 'ros_buildfarm' 

i found there /usr/bin/apt.py file related ros (robotics package) causes problem. maybe apt.py selected executed instead of apt file. renamed apt.py file , problem solved now!

cd /usr/bin sudo mv apt.py apt-archive.py