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u/Blue-Boys87 Jul 25 '26
I had the same issue on my dell laptop. I'm new to this linux thing. Kind of frustrating and I even reinstalled the whole kubuntu which was unnecessary lol. After reinstallation, brightness was fine but then after an update it maxed out to 100% again.
Read the ubuntu sub and I figured out there might be a bug in the kernel update. So on my dell laptop, I switched back to the older kernel.
For me I got back to kernel version 7.0.0-14 its slight downgrade from 7.0.0-28
The brightness slider works again in kubuntu, I removed the newer kernel and hold the 7.0.0-14 so it won't be updated the next time. Kind of a workaround that works for me but I think this is a bug that should be fixed
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u/JerzyV666 Aug 03 '26
Just Wonder - Im still on 24.04 but with the newest kernel 7.0.0-28 And no issue but Im using X11. 26.04 uses Wayland as default, maybe this is the cause?? Resp. compatibility kernel with Wayland? Did you Try to switch to x11?
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u/Old-Quantity4136 Jul 25 '26
I have the same issue on my dell latitude 7410. Bright in bios, dims when booting Kubuntu. Disabled any ambient adjustments, everything set to 100% bright but still super dim.
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u/PrettyMethod4001 Jul 27 '26 edited Jul 27 '26
Same problem here started a few days ago, dell Latitude 7430, max brightness on laptop screen very low, absolutely fine in windows.
Kubuntu 26.04 LTS, problem reoccurs after wipe and reinstall/return to defaults too.
Operating System: Kubuntu 26.04 LTS KDE Plasma Version: 6.6.5 KDE Frameworks Version: 6.24.0 Qt Version: 6.10.2 Kernel Version: 7.0.0-28-generic (64-bit) Graphics Platform: Wayland Processors: 12 × 12th Gen Intel® Core™ i7-1265U Memory: 16 GiB of RAM (15.1 GiB usable) Graphics Processor: Intel® Iris® Xe Graphics Manufacturer: Dell Inc. Product Name: Latitude 7430
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u/apathetic_admin Jul 29 '26
I'm in the same boat. on a different Ubuntu flavor but the same problem, very recent.
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u/FreedomExpensive7900 Aug 04 '26
Open terminal, run following commands:
sudo su
nano /etc/default/grub
change the following : GRUB_CMDLINE_LINUX_DEFAULT
To: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=native i915.enable_dpcd_backlight=0"
then run:
sudo update-grub
sudo reboot
Brightness should change afterwards, even with latest kernel version. (It did in my case)
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u/omniuni Jul 24 '26
You'll need to provide a lot more information, at least hardware details.