After awakening from a regular sleep in Ubuntu 18.04, I often notice strange characters bugs in the Gnome interface. I link screenshots to this post. The only way I found to fix it is to perform a reboot.
It happens to me with French and English interfaces, and it happened with 2 different Ubuntu 18.04 installations on my computer.
I though this issues may be related to How to fix missing characters from font after awakening from suspend?, still none of the proposed solutions worked for me, and my characters didn't disappeared, but changed.
I guess it may be related to interference between my NVidia card (840M), the Intel Display HD card, and Gnome...
I am using NVidia additional drivers : GM108M (Geforce 840M) nvidia-driver-390 (proprietary, tested), on an Asus computer - UX303ln.
Thank you for reading!
Desktop characters bug screenshot
Application launcher characters bug screenshot
EDIT
I faced a new issue : after going to sleep mode, my computer wasn't able to recover from the dark screen.
I even tried ALT+SYST+[R, E, I, S, U, B] to reboot the computer, without success. I had to hard reboot by holding the power switch. One week ago, a similar problem caused my SSD to be corrupted. I had to buy a new one and that why I could say I tried two different Ubuntu installation... Maybe this is linked to the Data corruption issue with the new Linux version? https://www.phoronix.com/scan.php?page=news_item&px=Linux-4.19.8-Released
By looking more specifically for this dark screen problem here https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1774950 , I discovered the "nouveau" driver issue concerning nVidia graphics cards. Two possibilities are proposed : downgrade the Linux Kernel to 4.14 or disable nouveau through GRUB. I have chosen the second option for now. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1774950/comments/24
Set
nouveau.modeset=0
to GRUB_CMDLINE_LINUX in the /etc/default/grub file, after that run:
sudo update-grub
sudo reboot
I will answer this issue in a few days if I found out the problem not to occur anymore.
Cheers.