How to fix ‘E: Could not get lock /var/lib/dpkg/lock’ Error in Ubuntu

Sometimes when users try to install an application by executing the usual apt command on Ubuntu, they get the following error:

Other users might encounter similar ones like :

In this article we will shall provide some effective methods to get rid of this kind of errors.

1 – Identify and kill all apt or apt-get related processes

This error can occur due to several reasons. Since this is a locking situation, it could be that the apt or apt-get commands are being used by some other processes preventing therefore other programs from using them. Some applications like Synaptic Package Manager or Ubuntu Software Center are using this package management utility.

Read : How to install and uninstall applications on Ubuntu ; A Beginner’s guide

It won’t actually harm to kill an apt or aptitude process unless it is currently performing a package installation. Killing a dpkg process however might not be a good idea, since if dpkg is currently active, .i.e. manipulating the package database, the package database will become inconsistent or in other words corrupted.

To kill the processes that are using the apt tool, run the command below:

ps aux | grep -i apt

The id of the process which invokes apt or apt-get is displayed above, .i.e. 24623. We will now kill this process in order to release the lock using the sudo command below:

sudo kill -9 24623

In your case, just plug in the process id that you obtained above.

Another alternative would be to kill all instances of the programs that are running apt or apt-get using killall:

sudo killall apt apt-get

2 – Remove the lock file

In case you had no other processes running apt or apt-get commands in your current session, then the problem might be caused by the lock file that was created at some time in the past due for instance to apt processes not terminated properly.

Read: How to speed up Linux

Since the lock files are still around, we should first make sure no other process is using it before removing it. This is because it is not good practice to remove the lock file without terminating the program that’s holding the lock first, since this could interrupt an ongoing installation or cause corruption.

In order to identify the process that owns the lock file, we will use the command lsof as shown below :

lsof /var/lib/dpkg/lock
lsof /var/lib/apt/lists/lock
lsof /var/cache/apt/archives/lock

The output might look like the following :

If one of these commands returns a result, it will display the process id that owns the lock file. The PID shown above is 12127. Go ahead and run the kill command below :

sudo kill -9 12127

You can now remove the lock file with the command:

sudo rm /var/lib/apt/lists/lock

You may also have to delete the lock file in the cache directory by running the commands:

sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock

Conclusion

We have provided two methods to deal with a rather common problem faced by many users on Ubuntu and similar distros when they run apt or apt-get . This is the lock issue that prevents other processes from executing these installation commands. Terminating these processes or removing the lock file can help solve this problem.
In case you have other methods that help solve this error, do not hesitate to share it with us.

amin nahdy

Amin Nahdy, an aspiring software engineer and a computer geek by nature as well as an avid Ubuntu and open source user. He is interested in information technology especially Linux based ecosystem as well as Windows and MacOS. He loves to share and disseminate knowledge to others in a transparent and responsible way.

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