The Namespace Steam Demanded

16:35 - Steam won’t launch. New error message:

Steam now requires user namespaces to be enabled.

Link to GitHub. Helpful. I run Gentoo. The standard fixes probably won’t work.

17:28 - Tried the obvious:

sudo sysctl kernel.unprivileged_userns_clone=1

sysctl: cannot stat /proc/sys/kernel/unprivileged_userns_clone: No such file or directory

The kernel parameter doesn’t exist. Because on Gentoo, if it’s not compiled in, it doesn’t exist.

17:45 - Checked my kernel config:

zgrep USERNS /proc/config.gz

CONFIG_USER_NS=y

User namespaces are enabled. But unprivileged user namespaces? That’s different.

zgrep UNPRIVILEGED /proc/config.gz

Nothing. The option doesn’t exist in newer kernels the same way.

18:00 - The actual fix for modern kernels:

# Check current setting
cat /proc/sys/kernel/unprivileged_userns_clone
# If file doesn't exist, namespaces are controlled differently

# For kernels 5.x+, check:
cat /proc/sys/user/max_user_namespaces

My kernel had max_user_namespaces set to 0. Steam needs it non-zero.

sudo sysctl -w user.max_user_namespaces=15000

18:10 - Steam launches. Games work.

Made it permanent:

echo 'user.max_user_namespaces=15000' | sudo tee /etc/sysctl.d/99-userns.conf

The Lesson: When Steam says “enable user namespaces” and the internet says kernel.unprivileged_userns_clone=1, that’s for older kernels. Modern kernels (5.x+) use user.max_user_namespaces instead.

Gentoo teaches you kernel options. Whether you wanted to learn them or not.

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The error message links to a GitHub page. The GitHub page assumes you’re on Ubuntu. Gentoo users get to figure out the translation.