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A few days ago I updated Python from version 3.6.7 to 3.7.1 based on the instruction found here on an Ubuntu 18.04. Since then, a No Entry Sign appeared on the top of the Desktop and the GUI Software & Update and Terminal shortcut Ctrl+Alt+T stopped working.

I tried several solutions including sudo apt update and sudo apt upgrade but none worked. More precisely, when I run sudo apt update I receive the below result.

Traceback (most recent call last):
  File "/usr/lib/cnf-update-db", line 8, in <module>
    from CommandNotFound.db.creator import DbCreator
  File "/usr/lib/python3/dist-packages/CommandNotFound/db/creator.py", line 11, in <module>
    import apt_pkg
ModuleNotFoundError: No module named 'apt_pkg'
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook
    from apport.fileutils import likely_packaged, get_recent_crashes
  File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>
    from 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>
    from apport.packaging_impl import impl as packaging
  File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 24, in <module>
    import apt
  File "/usr/lib/python3/dist-packages/apt/__init__.py", line 23, in <module>
    import apt_pkg
ModuleNotFoundError: No module named 'apt_pkg'

Original exception was:
Traceback (most recent call last):
  File "/usr/lib/cnf-update-db", line 8, in <module>
    from CommandNotFound.db.creator import DbCreator
  File "/usr/lib/python3/dist-packages/CommandNotFound/db/creator.py", line 11, in <module>
    import apt_pkg
ModuleNotFoundError: No module named 'apt_pkg'
Reading package lists... Done
E: Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/lib/command-not-found/ -a -e /usr/lib/cnf-update-db; then /usr/lib/cnf-update-db > /dev/null; fi'
E: Sub-process returned an error code

I wonder if anyone can help to repair the problem or downgrade to previous version of Python. I appreciate your help in advance.

Meysam Majnooni
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    Have you tried reversing the commands you used to implement your chance (checking history may help jog your memory as you're using a different release of Ubuntu to the instructions). I don't know if dpkg-reconfigure uses python (tools that use python won't work until you fix it), but it just re-runs the post-install script which you may need to do manually. – guiverc May 02 '19 at 09:55
  • Severe breakage when changing the default system Python is expected behavior. Avoid doing that. Remember to provide feedback to that blogger: Their careful, detailed instructions broke your system quite horribly. – user535733 May 02 '19 at 14:54
  • Does this answer your question? ModuleNotFoundError: No module named 'apt_pkg' error – karel Feb 01 '20 at 16:56

0 Answers0