Unable to lock the administration directory (/var/lib/dpkg)

Sometimes when you try to install or update the software on your Ubuntu system, you might see error messages like this: Unable to lock directory (/var/lib/apt/lists) or Unable to lock the administration directory (/var/lib/dpkg).
All these errors are the same and generally occur when another process is using the package manager, or there are leftover lock files from previous processes.

Here’s a guide to fix this common package management lock issue without directly deleting lock files, which can be risky.

Why Not Remove Lock Files?

Many blogs suggest directly removing the lock files to resolve this issue. However, this approach is not recommended because it can cause more harm than good. Lock files exist for a reason: they prevent simultaneous access that can corrupt the package manager database and filesystem. Deleting these lock files can lead to more serious problems. Instead, it’s better to terminate the processes that are holding these locks.

How to Check for Running Processes?

First, check if there is another package process running. Execute the following command in your command line and note their process IDs (PIDs) :

ps aux | grep -E 'apt|dpkg|apt-get'

Look for any processes related to apt, dpkg, or apt-get.

How to Terminate the Identified Process?

If you find any processes in the last command for finding running processes, you can terminate them using the below command:

sudo fuser -vik -TERM /var/lib/dpkg/lock /var/lib/dpkg/lock-frontend /var/lib/apt/lists/lock

This command will prompt you to confirm the termination of any process holding these lock files.

While kill -9 is there to forcefully terminate processes, fuser is a more controlled and safer method for resolving lock file issues, especially in critical directories like /var/lib/dpkg. By using fuser, you ensure that processes are terminated properly, reducing the risk of system instability or data corruption. By this means this tutorial doesn't used kill command.

How to Forcefully Terminate the Process? [Optional]

Even after performing the last command, If any processes are stubborn and don’t terminate with -TERM, use -KILL:

sudo fuser -vik -KILL /var/lib/dpkg/lock /var/lib/dpkg/lock-frontend /var/lib/apt/lists/lock

How to Reconfigure dpkg/Update the Package List??

After terminating the processes, based on your error execute one of the following commands:

For error: Unable to lock directory (/var/lib/apt/lists), execute the command to update your package list to ensure everything is updated and in sync:

sudo apt update

For error: Unable to lock the administration directory (/var/lib/dpkg, execute the command to reconfigure dpkg to ensure everything is in order:

sudo dpkg --configure --pending

If you still encounter problems, restarting your system might help clear any lingering issues. 😃💡