I recently upgraded from Debian Stretch to Debian Buster (or Debian 9 to Debian 10). I hadn't done anything unusual with my system, so I was expecting a smooth upgrade process. It did work smoothly, with one exception: my monitor simply would not wake up after a screen timeout.
The problem
The monitor just refused to wake up after time out, even if I unplugged and replugged its power cord (its own one, separate to the computer). The monitor reported no signal from the computer. However, the computer was actually working fine during this time - the light was on, and the keyboard caps lock key light toggled on and off; a sign that it was indeed working.
But with no way to see any of the screen, I simply couldn't do anything to restart the machine except for a hard restart (turning off the computer with the power button and turning it back on). Needless to say, this was not good since I had open unsaved files on my desktop!
I couldn't find anything actually helpful on the internet. I felt that since I hadn't done anything unusual with my system, nor had I changed monitors or hardware, that it should "just work"! I fiddled with a lot of the power management settings, but nothing helped.
The situation was so disruptive to my work that I almost (but not quite!) considered re-installing Debian from scratch, although that was going to be a big pain to set up my desktop again, etc etc. No, there had to be an easier way.
The solution
In the end, I just booted up from an older kernel in the startup menu. That seemed to fix the problem. I hate using older software, the whole point of updating was to be up to date, but at least I could get to a workable situation where I was able to safely get in and out of my system without hard shut-downs.
I'm hoping that whatever the kernel issue was, that it'll be fixed in one of the later updates of Debian Buster. I don't know enough about Debian and its update process to know if that's even likely or not.
But, if you're experiencing the same issue, try booting up from an older kernel. It'll at least provide a temporary solution to your problem until the actual cause of it is determined. I'm thinking I might change my grub settings to default to the older kernel for now. That way I don't inadvertently boot into the new kernel and keep running into the same problem.
Debian is supposed to have high stability!
I would not call this a stable situation. Although Debian prides itself on its stability, I was not expecting that a change in kernel would cause this many issues. Yes, I get that communications between computer and monitor are complicated, but at the same time, an upgrade should not make those things worse. My monitor is an HP that's been around awhile, so it's not anything weird.
I'll update this later if I have any more news on how to fix this problem more permanently (without having to resort to an older kernel). In the meantime, I'm glad that there is at least this temporary working solution of the older kernel.
Update - November 10, 2019
I also tried another approach, which was disabling kernel modesetting. That was a nightmare! The system didn't want to boot, and I had to change the settings back to what they were using a recovery disk.
Final solution
The final solution was... after getting frustrated at having to use an old kernel... to finally switch to another distro. I switched to Linux Mint and have not looked back since! It was so fast to customize my desktop, and I'm thrilled with it.
The problem
The monitor just refused to wake up after time out, even if I unplugged and replugged its power cord (its own one, separate to the computer). The monitor reported no signal from the computer. However, the computer was actually working fine during this time - the light was on, and the keyboard caps lock key light toggled on and off; a sign that it was indeed working.
But with no way to see any of the screen, I simply couldn't do anything to restart the machine except for a hard restart (turning off the computer with the power button and turning it back on). Needless to say, this was not good since I had open unsaved files on my desktop!
I couldn't find anything actually helpful on the internet. I felt that since I hadn't done anything unusual with my system, nor had I changed monitors or hardware, that it should "just work"! I fiddled with a lot of the power management settings, but nothing helped.
The situation was so disruptive to my work that I almost (but not quite!) considered re-installing Debian from scratch, although that was going to be a big pain to set up my desktop again, etc etc. No, there had to be an easier way.
The solution
In the end, I just booted up from an older kernel in the startup menu. That seemed to fix the problem. I hate using older software, the whole point of updating was to be up to date, but at least I could get to a workable situation where I was able to safely get in and out of my system without hard shut-downs.
I'm hoping that whatever the kernel issue was, that it'll be fixed in one of the later updates of Debian Buster. I don't know enough about Debian and its update process to know if that's even likely or not.
But, if you're experiencing the same issue, try booting up from an older kernel. It'll at least provide a temporary solution to your problem until the actual cause of it is determined. I'm thinking I might change my grub settings to default to the older kernel for now. That way I don't inadvertently boot into the new kernel and keep running into the same problem.
Debian is supposed to have high stability!
I would not call this a stable situation. Although Debian prides itself on its stability, I was not expecting that a change in kernel would cause this many issues. Yes, I get that communications between computer and monitor are complicated, but at the same time, an upgrade should not make those things worse. My monitor is an HP that's been around awhile, so it's not anything weird.
I'll update this later if I have any more news on how to fix this problem more permanently (without having to resort to an older kernel). In the meantime, I'm glad that there is at least this temporary working solution of the older kernel.
Update - November 10, 2019
I also tried another approach, which was disabling kernel modesetting. That was a nightmare! The system didn't want to boot, and I had to change the settings back to what they were using a recovery disk.
Final solution
The final solution was... after getting frustrated at having to use an old kernel... to finally switch to another distro. I switched to Linux Mint and have not looked back since! It was so fast to customize my desktop, and I'm thrilled with it.
