add-official-kali-linux-repositories

Open sources.list and comment all lines with # in front

The simplest way is to edit the /etc/apt/sources.list

 leafpad /etc/apt/sources.list

If you’re serious about keeping Kali Linux stable, then remove or comment every-line with # at the front and add the following lines..

## Regular repositories
deb http://http.kali.org/kali kali main non-free contrib
deb http://security.kali.org/kali-security kali/updates main contrib non-free
## Source repositories
deb-src http://http.kali.org/kali kali main non-free contrib
deb-src http://security.kali.org/kali-security kali/updates main contrib non-free

Save and close the file.

Step1

apt-get clean

STOP:  To fix Kali apt-get slow update follow the guide on fixing Kali apt-get slow update.

To switch repositories to a different mirror of your choice, follow the guide on changing repositories to a different mirror.

Step2

apt-get update

Step3

apt-get upgrade

Step4

apt-get dist-upgrade

That’s it, you’re set.if you want to know more details click here