1. pacman produces an error when installing packages
error: restricting filesystem access failed because Landlock is not supported by the kernel!
error: switching to sandbox user 'alpm' failed!
This issue applies to Arch Linux and it’s derivatives (CachyOS, EndavourOS)
You simply need to enable one thing in config.
Go to pacman.conf: sudo nano /etc/pacman.conf
Find the #DisableSandbox and remove the #
(if there’s no such option - just write it in options section)
Save and exit nano: Ctrl+S, Ctrl+X
2. pacman outdated keys
When pacman gives error about unsigned packages when updating the system, update keyring.
sudo pacman -Sy archlinux-keyring
3. Steam, Mesa and anything else stopped properly working after pacman -Syu
This is due to the transition to the recent LLVM release (currently, 21 to 22).
Everything else should work without the issue in theory because all packages in official repositories were transitioned.
What doesn’t work - is our old mesa (and problems with dionkill’s repository)
But there’s a hotfix - mesa 26.0 compiled with LLVM 22.
https://mega.nz/folder/B2V1kSrA#rZLRktqJW8aSWE9WnI9-Zg
And you can install it with terminal.
Open it up, type sudo pacman -U and then select all package files and drag them from file manager to terminal.
It will type them after the command.