Nitro 5 AN515-42-R9G7 put to hibernate/suspend/sleep to RAM using Kubuntu 18.04.1 doesn't wake up.

@zypaza Perhaps it could be the ubuntu power manager, I am not sure if theirs is different form Arch, you could try tinkering it or replace it with other managers. In the end there are two possibilities 1) A bug got patched in kernel 4.18.9; 2) The BIOS is bugged; or which is most likely the case 3) both 1 and 2. I am sorry I can't be of more help, I just moved on to Arch (installed it on a 32gig USB 3.0 thumb, drive runs great, learned a bunch about linux and I didn't have to mess with any the SSD partitions) while Ubuntu gets a fix or the bios does. Acer isn't giving us any feedback about problems nor we have anywhere to contact them where they won't think we didn't try all the fixes that are just a couple of google searches away.

If you really need Ubuntu you could perhaps try 18.10 and try to see if you can run it stable with kernel 4.18.9. As a tip on 18.10 tty1 sometimes doesnt load the GDM (login screen), you can switch back and forth between tty2 tty3 and tty1 and at some point the GDM will launch, else you could try just loging in into tty2 and run startx (you will load the default gnome environment), after which if you log out and go to tty1 it should load the ubuntu login screen, another fix could be to perhaps just disable gdm with systemctl and login the old way through tty1.

@zypaza Oh yes, do update the bios, mine is at 1.09, it was when I was on 1.06 that my laptop crashed randomly (while using windows) and couldn't even do a windows restore properly so I had to reinstall windows fresh. Acer lists BIOS 1.08 as the latest, however if you manually update the bios through windows device manager you can actually get 1.09, I would suggest to first test 1.08 though and if that doesn't work try 1.09. If you test windows with your current BIOS you will eventually notice random performance drops (cpu would throttle to 0.36GHz on windows) specially when pluging and unpluging the laptop, this was mostly fixed on 1.08+, so the patch might have been related to power battery/power consumption/supply/management, but that is only my theory. Give the BIOS update a try and if that doesn't work with the 4.19 kernel then changing kubuntu power managers could be another way to go. if you go to the Arch wiki and look for the power management section you might find a hint on how power in management works: Power management with systemd > Power managers 

zypaza yeah after the you get windows back you would want to upgrade the BIOS via acer download page and then to 1.09 through windows devices manager, expand the firmware list and right click BIOS or whatever is in there and to check for update, windows should proceed to update to 1.09. There are very small chances that the laptop is incompatible with linux, and if it is, it might be because of a buggy BIOS or a piece hardware that is not supported by the kernel all which can be addressed via software, although there are small chances that kernel contributors might want to look into this specific problems, however since I notice that even windows has performance hicups it might all really be the BIOS.

Also contact acer for an e-Recovery media, it is free, but they only give you one free after that you can buy it from them for 50$ or so, anyhow that should restore the laptop to default, windows and all (except BIOS that will remain unchanged). Although I must warn it took me 4 chats with acer support, an angry review and 1 month until they sent the usb since they were constantly "out of stock".

Also think it doesn't void warranty if you install linux alongside windows, but if you fully replace windows then yeah that might void it, although now mirosoft remembers which computers have a license, apparently they make an unique identifier of the computer combining data from the hardware components so if you reinstall windows while connected to the internet it should get activated automatically. I did a fresh install of windows after my laptop died, using a live usb with windows donwloaded from their website (any one can download it, no info needed) and it didn't ask me for activation because it knew the computer has license, although I think there are limits to the amount of reactivation and hardware changes (so people don't slowly change one computer into a whole different computer by changing one component at a time). So you should be able to save you activation code.

It was most likely the BIOS 1.06, freezes like that happened to me while on windows (I didn't get to test ubuntu long enough to experience freezes before the laptop died while using windows 10). So you should be freeze free now, fingers crossed for Acer updating the BIOS so that we can load Ubuntu without special parameter.