crashes on startup, "No usable sanbox!"

[Walter (voidwalter)]

BrowserOS installed via the official .deb package fails to launch on Ubuntu 24.04 64-bit with a fatal Chromium sandbox error.

FATAL:content/browser/zygote_host/zygote_host_impl_linux.cc:132] No usable sandbox!

browseros --no-sandbox this is disabling security sanbox(don't do it)

If you are running on Ubuntu 23.10+ or another Linux distro that has disabled unprivileged user namespaces with AppArmor, see
https://chromium.googlesource.com/chromium/src/+/main/docs/security/apparmor-userns-restrictions.md

Solve it:

sudo sysctl -w kernel.apparmor_restrict_unprivileged_userns=0 It will temporarily disable this restriction

permanent:

echo 'kernel.apparmor_restrict_unprivileged_userns=0' | sudo tee /etc/sysctl.d/60-allow-userns.conf sudo sysctl -p /etc/sysctl.d/60-allow-userns.conf

[Nikhil (shadowfax92)]

This is a great writeup — thank you for not just fixing it but documenting the actual cause. You nailed it: Ubuntu 23.10+ (and 24.04) restrict unprivileged user namespaces via AppArmor, which kills Chromium's sandbox, and re-enabling userns is the right fix — not --no-sandbox, which (as you correctly warn) just turns security off rather than fixing anything.

For anyone landing here from a search, follow exactly what Walter (@voidwalter) posted. And on our side, this is a packaging gap worth closing — the .deb should handle the AppArmor profile so people don't hit this at all. Closing as resolved since the fix is solid and documented, but it stays searchable. Thanks again.