I don't know how and when it happens but I noticed command-not-found works now: typing a command for running an uninstalled program brings me advice on how to install the correct package. However, the update-command-not-found command still gives me the same error for the aptosid repo, but after updating the debian repos cache: I: Writing data for ftp.fr.debian.org_debian_dists_sid_Contents-i386.gz ... . done I: Writing data for ftp.fr.debian.org_debian_dists_experimental_Contents-i386.gz ... . done I: Writing data for oscar.aptosid.com_debian_dists_sid_Contents-i386.gz ... Traceback (most recent call last): File "/usr/sbin/update-command-not-found", line 95, in <module> write_db_apt_file() File "/usr/sbin/update-command-not-found", line 72, in write_db_apt_file write_db_core(fobj) File "/usr/sbin/update-command-not-found", line 51, in write_db_core section, package = package.strip().rsplit('/', 1) ValueError: need more than 1 value to unpack