Was the printer running before? The more information you share, the easier is finding a solution.
What did yo do with the printer, before this message was displayed?
As your setup is not running everything can cause that issue.
On what platform is Klipper running? The mentioned i5-4300U suggests a mobile platform.
I’m not a Linux expert but maybe there are missing rights for the involved components here.
Yes it does. Especially, Ubuntu desktop versions tend to have some quirks that spoil Klipper.
Your error is not related Moonraker but Klipper itself and can have multiple reasons (the OS being one of them). See Issues flashing the printer board