In the update-command-not-found implementation here: /usr/sbin/update-command-not-found
the following lines seem important: command_files = glob.glob("/var/lib/apt/lists/*Contents*") if len(command_files) > 0: col = DbCreator(command_files) col.create(db) If I understand this correctly, it is looking for certain files in the /var/lib/apt/lists directory, specifically files named like *Contents*. However, on my system there are no *Contents* files in that directory (the directory exists but the files there have different names, nothing with "Contents") so command_files becomes empty and consequently no database is created, and no error message is given, since the len(command_files) > 0 condition is not satisfied. So, it seems like the update-command-not-found implementation assumes that certain files in /var/lib/apt/lists/ are named in a certain way, but in my case the files there are named differently and then no database is created. / Elias När du har kontakt med oss på Uppsala universitet med e-post så innebär det att vi behandlar dina personuppgifter. För att läsa mer om hur vi gör det kan du läsa här: http://www.uu.se/om-uu/dataskydd-personuppgifter/ E-mailing Uppsala University means that we will process your personal data. For more information on how this is performed, please read here: http://www.uu.se/en/about-uu/data-protection-policy