No irq handler for vector / Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0

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This solved the issue for me, no more errors and it boots normally into manjaro.
You can just copy the whole string in a tty.
To enter a tty just press ctrl+alt+f3 when the error appears at boot

sudo sed "s/\(GRUB_CMDLINE_LINUX=\)\"\"/\1\"acpi_osi=Linux acpi_backlight=vendor\"/" /etc/default/grub -i

after that

sudo update-grub

then just reboot and everything should be fine.

hope this will help you :smiley:

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