How to fix E: Could not get lock /var/lib/apt/lists/lock. It is held by process 1044 (packagekitd)

Question

Recently, I have bought a 64GB SD card for dual booting Ubuntu on my computer. It works at first, but when I try to run

sudo apt upgrade

It gives me this:

E: Could not get lock /var/lib/apt/lists/lock. It is held by process 1044 (packagekitd)

I have tried the following:

sudo apt autoremove
sudo apt clean
sudo apt autoclean

But it still gives me this error. Any help?

Answer 1

sudo service packagekit restart

worked for me.

Original answer: https://askubuntu.com/a/1286010