Same here, everything works fine till I try to update it to latest version. Reset everything tried again. Still same issues as you. Need help.

Are you able to pin-point the problem to a specific package upgrade? Can you go back to the working versionand upgrade only some packages at a time until you find the one that introduces this problem for you?

Start first with the kernel, then maybe gdm3, then maybe Xorg.

I'm updating it again in a fresh install, there's a problem with "dpkg directory already exists" If that has anything to do with it. I'm going to try...
login to tty1
apt-get update
apt-get upgrade -y
apt-get install -f gdm3
But the problem is when I'm on the gray screen I can't get my terminal to open, there's no mouse. So I'm pretty stuck.

Coming up with a lot of dpkg warnings. Unanle to delete old directory /etc/kernal/signed_postinst.d directory not empty. A few other warnings as well could it be that?

I think I have over 40 warnings dpkg unable to delete old directory. I'm going to try to attempt to fix them.

Still no use, just stuck on a gray screen, can't open uo terminal. Can't do anything. Everything was fine fixed the packages I think. As soon as I shut it down and then try to start it up again gray screen. Please any advice would be highly appreciated.

Found out what it is... Grub installation failed. 'grub-pc' package failed to install into target.

After maybe 4 hours, I did it. I'm not sure if this person came to the gray screen by doing an update like I did or did a fresh install. I was updating mine just as it was about to finish it stopped because I ran out of space so I ran the command apt autoremove to clear some space then turned it off and then came to the gray screen. So I'm not sure if it was because I didn't fully finish the update or if it was because I ran that command. I tried to do a fresh install but grub wouldn't install. So I don't know if that is a separate issue or part of it. To fix the grub issue I selected no on mirror sharing then the grub installed just fine. I used a usb, but didn't select graphical install I selected install. So I don't know if I'll run back into this problem but not sure if I want to update it to the latest version just in case. Let me know if you need help. I will try to help because I tried everything out there. In a way I enjoy these problems just hate it when I can't fix it. Can you suggest how I can clear space for the OS next time properly because that command probably deleted some essential things :)

Update, something to do with the update. Update installed fine won't allow me to login or do anything just a gray screen.

Fixed it by adding the nomodest into the code just before booting up into it. But now it's like the screen shot this person added glitchy it just about loads in.

sir can u give your email address I will send the video of error .

sir I have installed old version of kali 2016 and kali Linux kde 2018.4 all works properly.
sir how to add nomodset in the bootloader

Does the new version work for you now? It only works for me after I added the nomodest but it still is very glitchy I don't think this is a permanent solution. I forgot how I did it but when you load in and you can choose kali or advanced options. Select kali then press e and I think it's the line that starts with Linux but you put it at the end. This won't be saved though you have to edit it and save it through terminal but I forgot. Search it online. You'll find it if you don't let me know and I'll try to help you.

I don't know why we have this problem though I think our bootloaders are broken.

This is the reason why it doesn't work.
nomodeset
The newest kernels have moved the video mode setting into the kernel. So all the programming of the hardware specific clock rates and registers on the video card happen in the kernel rather than in the X driver when the X server starts.. This makes it possible to have high resolution nice looking splash (boot) screens and flicker free transitions from boot splash to login screen. Unfortunately, on some cards this doesnt work properly and you end up with a black screen. Adding the nomodeset parameter instructs the kernel to not load video drivers and use BIOS modes instead until X is loaded.

Due to the age of the OS (Kali Moto [v1], Kali Safi [v2], Kali Rolling <= 2018.4), these legacy versions are no longer supported.
We will be closing this ticket due to inactivity.

Please could you see if you are able to replicate this issue with the latest version of Kali Linux - https://www.kali.org/downloads/)?

If you are still facing the same problem, feel free to re-open the ticket. If you choose to do this, could you provide more information to the issue you are facing, and also give information about your setup?
For more information, please read: https://kali.training/topic/filing-a-good-bug-report/