Strange graphics issues such as flickering application windows and inconsistent display lagging [duplicate]
Solution 1:
The -49 and -50 kernels are flawed, and have been withdrawn. There are graphics issues (possibly only with internal Intel video subsystems).
Boot your computer. At the GRUB menu, select the 2nd choice, Advanced Options (or some such), and select your -48 kernel, or earlier if you don't have -48, and run off of that for now.
Keep up to date with Software Updater and once you see the -51 kernel, or later, then choose it at next boot.
Update #1:
Start Synaptic and install these files (search for 5.8.0-48)...
Run:
ls -al /boot
Confirm that initrd.img-5.8.0-48-generic is there.
If it's not there, then run:
sudo update-initramfs -c -k 5.8.0-48-generic
Then:
sudo update-grub
reboot
At the GRUB menu, select Advanced Options, then select the -48 kernel to boot from.
Solution 2:
EDIT: THIS SOLUTION DOES NOT WORK, ONLY TEMPORARY
However I found a very simple solution that I didn't find here so I want to share it. I needed to reconfigure my window manager. It are the first two steps of this link
1.) Check the current running display manager by running command:
systemctl status display-manager.service
- Run command to reconfigure the default manager:
sudo dpkg-reconfigure gdm3
Where you replace gdm3 with the manager you have at Main PID: