My recently installed Ubuntu system is currently having issues with the command-not-found hook:

josh@sirius:~$ invalid-command
Unable to open binary database /usr/share/command-not-found/programs.d/i386-main.db: File read error
Unable to open binary database /usr/share/command-not-found/programs.d/i386-multiverse.db: File read error
Unable to open binary database /usr/share/command-not-found/programs.d/i386-restricted.db: File read error
Unable to open binary database /usr/share/command-not-found/programs.d/i386-universe.db: File read error
invalid-command: command not found

I have tried reinstalling and dpkg-reconfigureing both command-not-found{,-data} but these don't seem to have fixed it. Is it safe to delete these files, or do I have to run some program to recreate them? I should add that this was originally a 32-bit install that I reinstalled with 64-bit without formatting the disk.

2 Answers 2


On 20.04.4 LTS, this helped me:

$ sudo apt install --reinstall command-not-found

The -data package is no longer there.

I was getting something like:

$ kbounce
Sorry, command-not-found has crashed! Please file a bug report at:
Please include the following information with the report:

command-not-found version: 0.3
Python version: 3.8.5 final 0
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.1 LTS
Release:        20.04
Codename:       focal
Exception information:

unable to open database file
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/CommandNotFound/util.py", line 23, in crash_guard
  File "/usr/lib/command-not-found", line 90, in main
    cnf = CommandNotFound.CommandNotFound(options.data_dir)
  File "/usr/lib/python3/dist-packages/CommandNotFound/CommandNotFound.py", line 79, in __init__
    self.db = SqliteDatabase(dbpath)
  File "/usr/lib/python3/dist-packages/CommandNotFound/db/db.py", line 12, in __init__
    self.con = sqlite3.connect(filename)
sqlite3.OperationalError: unable to open database file

Right now, I get:

$ kbounce

Command 'kbounce' not found, but can be installed with:

sudo apt install kbounce

Edit 2020-12-16

The problem returned after a reboot. I debugged /usr/lib/python3/dist-packages/CommandNotFound/db/db.py and found the following:

$ ls /var/lib/command-not-found/ -l
total 3076
-rw-r----- 1 root root 3141632 gru 16 08:17 commands.db
-rw-r----- 1 root root    3253 gru 16 08:17 commands.db.metadata

So, the DB is there, but the permissions are wrong.

So I executed:

$ sudo chmod -R o+r /var/lib/command-not-found/

Now, it works again.

  • With me, the problem was that import apt_get wasn't working in /usr/lib/python3/dist-packages/CommandNotFound/db/db.py, this answer did the trick!, so symlink apt_pkg.cpython-36m-x86_64-linux-gnu.so apt_pkg.so.
    – Fee
    May 3, 2021 at 19:09
  • +1 for the chmod. That was all I had to do to fix it.
    – qwerty9967
    Jul 13, 2021 at 20:17
  • You are answering a different question. Aug 15, 2021 at 20:05

The database files for the 64 bit version are named amd64-*.db, while the 32 bit version ones are named i386-*.db. So apparently you have the 32 bit package installed when you should've had the 64 bit package.

What does this output?

apt-cache policy command-not-found{,-data}
  • In here, because apparently I can't format comments nicely: pastebin.com/6fqTMDAn
    – dutchie
    Jul 25, 2013 at 14:01
  • @dutchie, hm. Does this list both amd64-*.db and i386-*.db files? ls /usr/share/command-not-found/programs.d/. If so, it might be the old package just failed to remove those for some reason. So just manually removing them should fix your problem.
    – geirha
    Jul 25, 2013 at 18:02

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