Ubuntu Version:
Ubuntu 25.10
Desktop Environment (if applicable):
GNOME
Problem Description:
apt update fails with a 404 on http://archive.ubuntu.com/ubuntu/dists/questing/main/binary-arm64/Packages .
Relevant System Information:
It fails on the arm64 based ThinkPad X13s laptop.
Screenshots or Error Messages:
What I’ve Tried:
I am able to successfully ping both archive.ubuntu.com and us.archive.ubuntu.com
That repository contains packages for amd64 and i386, but not ‘ported’ architectures.
The ported architectures are found at https://ports.ubuntu.com/
If your arm64 system is using Index of /ubuntu/dists/questing/main your sources have been corrupted and need correction; a quick opening of that link in your browser will confirm its incorrect (arm64 like ppc64el, armhf, s390x, riscv64 etc are ports), ie. you’ll find the packages at Index of /dists/questing/main
Thank you @guiverc for the hint .
Anyway, I cleared out the “/etc/apt/sources.list.d/ubuntu.sources” and ran “software-properties-gtk” (thanks to AI search) and it’s all happy now 
Great that you got this sorted out. We love it when a plan comes together
To help the community, please mark the relevant post as the solution (post number 2).
This gives credit to the user who helped and also let’s others know there is a solution in case they experience something similar.
Thanks
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