Ubuntu dpkg lock error

Error on ubuntu:
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

Solution:
You have two errors here. 

1. You are missing a GPG key
2. The dpkg lock file is locked.

You should fix (2) before you fix (1).

2. Open a terminal and type

lsof – List Of Open Files

Code:

sudo lsof /var/lib/dpkg/lock

You can then either close that program, restart your PC or send a -TERM to the program with the lock by using kill and the pid.

Code:

sudo kill <pid>

After killing the process the dpkg needs to be configured else it will throw this error:
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. 

Code:

sudo dpkg --configure -a

1. Only if required:
After that you need to import the key.

EDIT: Added command.

Code:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 2EBC26B60C5A2783

then type

Code:

sudo apt-get update

Source:
https://ubuntuforums.org/showthread.php?t=1858466