Issue – Updating kali-linux-2024.4-installer-amd64 on VirtualBox – Errors while processing kali-desktop-base

The key error line:
update-alternatives: error: alternative path /usr/share/desktop-base/kali-theme/login/background.svg doesn't exist

Go to that file folder location (/usr/share/desktop-base/kali-theme/login). You should see 3 “files” that are not actually files but rather are symlinks (symbolic links) – “background”, “background.svg”, “background-blurred”. Instead of regular display images, at least one icon is a giant red background with a white X in the middle, indicating the source that the symlink points to doesn’t exist. I discovered they were symlinks by right-clicking the file and looking at its properties btw. Looking at the properties will also tell you what filename it’s looking for. In my case, the symlinks were named “background.svg” and “background-blurred”, but they pointed to files “login.svg” and “login-blurred” (no file extension) respectively.

Solution:

Download a pretty picture that you would like for a login screen.
Navigate to the symlink files, right-click on them and find “Link Target” (where the symlinks point to). This will be the destination of the file that you are going to copy.
The folders where both the symlinks and actual pictures are are both restricted, so you will need higher privileges, meaning you will need sudo.

sudo cp srcFile destFileLocationWithFilename
sudo cp ~/Downloads/prettyPic /usr/share/backgrounds/kali/login.svg
sudo cp ~/Downloads/prettyPic /usr/share/backgrounds/kali/login-blurred

References:
Linux forum
Kali forum