E: Could not get lock /var/lib/dpkg/lock-frontend — how to fix

E: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 2481 (unattended-upgr)
N: Be aware that removing the lock file is not a solution and may break your system.
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?

Quick fix: Wait a few minutes: it's usually unattended-upgrades or another apt window. Check with ps aux | grep -E 'apt|dpkg'. If no apt process is running at all, run sudo dpkg --configure -a.

What it means

Only one package manager can change the system at a time. The lock is held by another process, named in the message (unattended-upgr = automatic security updates, apt, apt-get, packagekitd = Software Center).

Fix 1: wait

On a freshly booted machine, automatic updates often run for a few minutes. Wait and watch:

ps aux | grep -E '[a]pt|[d]pkg'
# or wait until the lock is free:
while sudo fuser /var/lib/dpkg/lock-frontend >/dev/null 2>&1; do sleep 5; done

Close other terminals running apt and the Software Updater GUI.

Fix 2: the other process is stuck

If the process has been running for a long time with no CPU or disk activity, stop it gracefully:

sudo kill <PID>          # PID from the message

Then repair any interrupted installation:

sudo dpkg --configure -a
sudo apt -f install

Don't delete the lock files first

Removing /var/lib/dpkg/lock* while another process is really writing can corrupt the package database. Only if no apt/dpkg process exists (ps shows nothing) and the error remains after a reboot, remove the stale locks and repair:

sudo rm /var/lib/dpkg/lock-frontend /var/lib/dpkg/lock /var/cache/apt/archives/lock
sudo dpkg --configure -a

In scripts and cloud-init

Wait for the lock instead of failing. apt has a built-in option:

sudo apt-get -o DPkg::Lock::Timeout=300 install -y nginx

Last updated 2026-10-27.