X server doesn't "wake up" upon resume from suspend

I run 19.04 on a Lenovo Thinkpad X1 Carbon (6th gen) HW manual. I've been using Ubuntu on it since I bought it in December 2018, and since then suspend/resume has worked without incident.

There used to be some problems with this laptop, but Lenovo provided a BIOS update to allow it to go into S3 sleep (whatever that means) and that's how I've always had my BIOS configured. I've used it a lot, suspending and resuming several times a day (not every day, but quite often) for months.

At some point about a month or so ago an 18.04 software update made it stop working. I upgraded to 19.04 and that didn't help. Now I can suspend the system just fine, and it goes into the "throbbing light" suspension state correctly. However when I wake the system up, the X server does not wake up.

I can hit Alt-F1 and get to a plain text console, and I see there the system has in fact correctly resumed from sleep. I can do a ps and see that Xorg is still running (often, inexplicably, on both tty7 and tty8). I have found no way to get it to wake up and prompt for a password to unlock the slept session, and I end up either killing the Xorg process(es) or rebooting.

What can I do to debug or investigate what's going on?

1 Answer

Update to 20.04.1

Internet searches return a variety of suggestions, none of which have worked for me. Had posted an updated workaround, only to have it suddenly fail. So count me among those looking for a workable solution -- until this is fixed.

-- Original Answer --

This is a kernel bug that affects a wide array of hardware. A quick search found the updated kernel (that fixes the breaking on resume-from-suspend) is not available for 19.04 yet (to potentially save you the trouble reverting to 18.04).

So the current fix would be to re-install 18.04, then check the kernel version:

uname -r

If it returns "4.15...," then upgrade manually to the hardware enablement stack ("hwe," which would eventually be auto-installed anyway) with:

sudo apt install --install-recommends linux-generic-hwe-18.04 xserver-xorg-hwe-18.04

All your troubles will melt away after this (at least, mine did).

uname -r
5.3.0-42-generic

(See history for earlier updates)