I am using KED in Kali Linux. I am not able to install softwares or update packages using Discover
Use command line then.
However I’d better ask in Kali Linux support forum.
@IamJamesWalter, welcome to the forum!
I am not familiar with Kali Linux. In my experience, Discover is not suitable to install system updates. I’ll admit my experience with Discover is limited to Kubuntu, Manjaro (KDE), OpenSuSE (KDE), and OpenMandriva. I’ll further admit that when I tried Manjaro, I probably didn’t give it a fair try since updating the system the first time using Discover broke the system. I should have used the package manager to do the updates. Even now on a few Ubuntu (Gnome) computers that I still manage, I ignore the automatic update tools in favor of using the terminal. Likewise, I find it better to use the command line for installing new software. A package management program such as Synaptic (Ubuntu), dnfdragora (OM), or whatever is available for your distro’s system is fine for checking installed and available programs and dependencies. However, it is always (imho) preferable to use the terminal for software management.
Since a quick check of the Duck[DuckGo] shows me that Kali uses apt, you would simply type:
sudo apt update
sudo apt upgrade
and that will take care of your regular system updates.
Also, I’ll assume that Kali has Synaptic package manager, so if you don’t already have it installed:
sudo apt install synaptic
Hope that helps!