Booting up with monitor turned off results in a black screen afterward

BeetlePie · 2026-01-14 12:59:14

Greetings,

I noticed that when I boot up my system with the monitor turned off and then turn it on after a few seconds, nothing is displayed on the screen but a blinking underscore. I researched about it on different forums and it seems to be related to a Kwin + Wayland bug, but I couldn't find deep information about the issue so I would like to know if there are other people here having the same problem. For some background: I have SDDM + KDE + Wayland on my computer. Recently I followed the instructions specified on the Arch Wiki about SDDM on Wayland and KDE, which implies adding some lines to the file located in "/etc/sddm.conf.d/10-wayland.conf" and installing "layer-shell-qt".

Despite the blinking underscore mentioned before, whenever the bug triggers, I can still use TTY 3 to log in or reboot the system. However, if the monitor is already turned on when the computer is booting, the system works just fine, which means the issue can be easily reproduced by booting the computer with the monitor turned off and then turning it on after a while. In fact, I just forced the problem to provide a log using the command "journalctl -b -1 -u sddm --no-pager", here's the pastebin link. For clarity, I used TTY 3 as mentioned before and then rebooted the system after the error occurred. And here's the current (healthy) session for contrast. I'm not looking for a fix but for proof that this is happening to other users as well to address the bug properly.

Last edited by BeetlePie (2026-01-23 23:22:08)

BeetlePie · 2026-01-23 23:19:20

I use a DP cable, if that helps also. It should be easy to reproduce so I'd like to see if other people experience this as well or if it is just me.

cryptearth · 2026-01-24 01:32:57

well - the "issue" is rather DisplayPort itself - and the firmwares of both the gpu and the monitor - not much software can fix
anyway - give LinusTechTips one or two views of thier several videos when they got bitten by using DP with the only solution "just reboot"
I can't explain it in detail but from what i understand its something about the handshake which, although DP is designed hot-plug, doesn't like being hot plugged

aside from that: given the effiency of modern switch mode power supplies and how soft-poweroff works: there's no reason to "turn off" your monitor since pretty much the late 90s
even you have a wall of 4x4 screens to pull off 16k there's hardly any difference between stand-by and soft-off - the only real difference is that the monitors controller isn't powered which in turn results in the auto-detect circuit no longer reacting when a signal comes in - or, tl;dr: i don't get why people keep "turning off" thier screens these days anyway - there's no benefit to it but only downsides and issues - to me these stupid "power" buttons should be gone and replaced by a power indicator only

solution for you: just don't "turn off" your screens - simple as that
and NO - there's no real "savings in power and cost" - it sums up to merely cents - over the entire year - it's little it's just noise in you electric bill

dimich · 2026-01-24 03:57:43

cryptearth wrote:

i don't get why people keep "turning off" thier screens these days anyway - there's no benefit to it but only downsides and issues - to me these stupid "power" buttons should be gone and replaced by a power indicator only

Sorry for offtopic, but let me disagree, at least for some reasons:
* There is always some standby current. It may be important if monitor has external power adapter and powered autonomously directly with DC.
* Many manufacturers make power indicators glowing and blinking like x-mas tree. Covering indicator with opaque duct tape is not a pretty fine workaround.
* While in Linux it is possible to configure primary/secondary output for multi-monitor setup, UEFI/BIOS often initializes all available outputs. Turning on all monitors at boot is annoying.

Regarding DP, it has dedicated 3.3V power pin (more current capable than HDMI, btw) and hotplug pin. OP issue looks like a software/firmware bug.

cryptearth · 2026-01-24 13:30:16

dimich wrote:

* There is always some standby current. It may be important if monitor has external power adapter and powered autonomously directly with DC.

I have not claimed anything else - just that difference bet "hot stand-by" and "cold power-off" is negligible even with multiple monitors over an entire year
in fact: given the required voltage and amperage (=wattage) to make an led glow despite rather little is likely the most in this entire low power state as the mere difference ranges only from just not trigger upon input signal to have the detection circuit not powered - that's a difference less than to power the led - and only shift to what signal has to be listened for: the change in input level vs pressing tge "power" button - but some kind of circuit has to be powered up at all times for any sort of stand-by - unless it's a hard cut like a rocker switch
also i see this flaw: devices with a deep sleep are designed gor constant wall power - devices designed for battery power are usually draw thier power directly from the device they connected to - so when the system (some mobile platform) is poweted off it no longer provides any power to the display anyway - make a power button as obsolete and useless as for wall powered devices
if you power a monitor meant to plugged into the wall feom a battery instead then that's your fault

* Many manufacturers make power indicators glowing and blinking like x-mas tree. Covering indicator with opaque duct tape is not a pretty fine workaround.

can't say i have encountered such in the past years
stand-by is usually a dim orange/red-ish while active is often light blue, green or white
i actually can't think of any screen going disco in either state - feel free to point some out

* While in Linux it is possible to configure primary/secondary output for multi-monitor setup, UEFI/BIOS often initializes all available outputs. Turning on all monitors at boot is annoying.

that one is actually quite confusing: why have multiple screens when you don't want to use them all anyway? people have thier reason to hook up 2, 3 or even more screens to thier system
if you don't use them all and have one just burn in all tge time without any just disconnect it
sorry - but i can't see any reason behind this - no matter if we talk about several minutes booting windows from spinning rust or just a few seconds for linux from a ssd

Regarding DP, it has dedicated 3.3V power pin (more current capable than HDMI, btw) and hotplug pin. OP issue looks like a software/firmware bug.

as mentioned: yes, DP is designed and meant to be hot plugable - and as also mentioned i can't properly explain it - but for sone reason most DP implementations seem to share the same quirk that DP just doesn't like hotplug

and as "turning off" the screens dorsn't have any benefit but in fact does cause problems for OP a valid option here is "then just don't do it"
sometines life is as simple and binary as this: do it and live with tge issues it causes - or don't and you're good to go

i'm just the one who stands up and speaks out loud (or writes down) - and by now i should be known for this
it's not like i don't accept others opinions even when they disagree with mine - but i also don't fear to call someone out being stupid or doing stupid stuff when it's obvious
and here it is obvious: op encounters an issue vaused by thier actions of "turning off" thier screens - i'm just the one who shouttts it out loud: then don't do it - because it does you nothing but cause trouble

digging around implementation quirks of DP or the firmwares of the screen or gpu - nah - if i would be such a 300+ iq genious it would be me who you call tech jesus - not that south-african dude - but i'm not so i keep it simple - which is backed by thousands of users having the exact same issue as OP each and every day - who am i - or we for that matter - to magically fibd that one blaxk magic voodoo spell to break this decade okd course?
the question has exact to answrs: not turn off to screens - or deal with that issue as anybody else firever

oh, btw, to that one limbo: hint, idmf you do know a solution - don't tell anybody but get yourself rich by selling it

Lone_Wolf · 2026-01-24 14:25:05

I've encountered the same thing with 2 different amd videocards / motherboards (same brand of mobo though) .

As for shutting down equipment or leaving it in standby :
You do know what damage short circuit can cause on devices in standby mode ?

I do and all devices I have that don't need to be powered on 24/7 are powered off when not in use.
(Those without off switches - such as microwave & TV - through external switches.)

seth · 2026-01-24 15:16:55

Errr… https://pastebin.com/f8u9EzgH is some minimal and useless SDDM logs.
Please post your Xorg log, https://wiki.archlinux.org/title/Xorg#General (SDDM defaults to that) and in doubt your complete system journal for the boot:

sudo journalctl -b | curl -F 'file=@-' 0x0.st

For an incredibly simple explanation: the X11 server will automatically enable all present monitors when it starts up, but none that show up later (you've to catch those events and enable them) but there could also be a hybrid GPU scenario (and the X11 server switching outputs)
You can always https://wiki.archlinux.org/title/Kernel … s_and_EDID (or depending on the driver also via X11 config)

If you're explicitly running SDDM on top of some wayland compositors, you'd have to look into their config options.

Disclaimer: I only read #1, #2 & #6

BeetlePie · 2026-01-24 21:35:28

cryptearth wrote:

solution for you: just don't "turn off" your screens - simple as that
and NO - there's no real "savings in power and cost" - it sums up to merely cents - over the entire year - it's little it's just noise in you electric bill

That is certainly not a solution but a patch. I'm aware that I can boot the system by turning on the monitor before the computer does, which is exactly what I started doing the moment I got the black screen consistently, otherwise I'd be facing the same black screen with each boot. I don't do it for power-saving reasons, I just have everything plugged to a power strip and I don't like to "forcefully" turn off the monitor through the power strip's button. Anyways, this issue should not happen since hot-plug is supported (as other users mentioned), so it's rather an abnormal behavior. On the other hand, I already stated in my first post that I'm not even looking for an immediate fix, not only because it is easily avoidable, but because this error might be a bug beyond our scope or my setup itself.

dimich wrote:

OP issue looks like a software/firmware bug.

The reason I suspect this is because I've been using Arch with KDE + SDDM + Wayland since I started on May last year and I was able to boot the system with the monitor turned off beforehand. There was, however, an arbitrary chance to get the same black screen throughout the months that I get now. Because it was very random, it was not especially bothering, but I could not reproduce it either to give it an explanation. Then I did some research for the sake of having my system fully functional and it was not until I configured the file located in "/etc/sddm.conf.d/10-wayland.conf", following the Arch Wiki instructions, that I got the black screen consistently. Doing what the Arch Wiki recommends for such a setup ends up "setting the Wayland compositor to KWin and enabling the wlr_layer_shell Wayland protocol extension". So can we really blame the DP or hardware when I could do a hot-plug until a few weeks ago? I think that if it is consistently failing after setting Kwin as the Wayland compositor, it has to be a Kwin bug, but that's just my theory.

Last edited by BeetlePie (2026-01-24 21:41:58)

seth · 2026-01-24 23:52:55

kwin_wayland will probably just continue the present config which was last changed when KMS kicked in (and likely before you switched on the display)
Do you have https://wiki.archlinux.org/title/SDDM#M … figuration ?
(Though even w/ that you'll likely have to switch on the monitor before kwin starts)

Otherwise see

seth wrote:

https://wiki.archlinux.org/title/Kernel … s_and_EDID

BeetlePie · 2026-01-25 00:37:29

seth wrote:

kwin_wayland will probably just continue the present config which was last changed when KMS kicked in (and likely before you switched on the display)
Do you have https://wiki.archlinux.org/title/SDDM#M … figuration ?
(Though even w/ that you'll likely have to switch on the monitor before kwin starts)

Yes, I did that as well.

Arch Linux

#1 2026-01-14 12:59:14

Booting up with monitor turned off results in a black screen afterward

#2 2026-01-23 23:19:20

Re: Booting up with monitor turned off results in a black screen afterward

#3 2026-01-24 01:32:57

Re: Booting up with monitor turned off results in a black screen afterward

#4 2026-01-24 03:57:43

Re: Booting up with monitor turned off results in a black screen afterward

#5 2026-01-24 13:30:16

Re: Booting up with monitor turned off results in a black screen afterward

#6 2026-01-24 14:25:05

Re: Booting up with monitor turned off results in a black screen afterward

#7 2026-01-24 15:16:55

Re: Booting up with monitor turned off results in a black screen afterward

#8 2026-01-24 21:35:28

Re: Booting up with monitor turned off results in a black screen afterward

#9 2026-01-24 23:52:55

Re: Booting up with monitor turned off results in a black screen afterward

#10 2026-01-25 00:37:29

Re: Booting up with monitor turned off results in a black screen afterward

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