How to Fix “Errors from xkbcomp are Not Fatal to the X Server” and “xinit: Connection to X Server Lost”

When trying to start an X session (such as launching a window manager using startx), users may run into this frustrating sequence of messages:

Errors from xkbcomp are not fatal to the X server  
xinit: connection to X server lost

This isn’t just a glitch, it often signals issues with the X Keyboard Extension (XKB) configuration or permissions and may lead to session crashes or an unstable graphical interface. Here’s everything you need to know to fix it permanently.

What Causes This XKB Error?

These messages originate from xkbcomp, a compiler tool responsible for translating human-readable keyboard layout files into binary maps the X server can understand. If something goes wrong during that compilation, you may see:

• Misconfigured or missing keyboard layout files
• File permission issues under /usr/share/X11/xkb
• Conflicts between user and system keyboard configs
• Incorrect or corrupted .Xmodmap or .xkb files in your home directory

While the error says it’s not “fatal,” it often precedes a more severe problem—like X crashing during startup.

Understanding xkbcomp and XKB

What is XKB?

X Keyboard Extension (XKB) is the X server’s subsystem for handling:

• Multiple keyboard layouts (us, uk, de, etc.)
• Modifier key functions (Ctrl, Alt, Shift)
• Special keys like Compose, Caps Lock behavior
• Key repeat rates and macros

What is xkbcomp?

xkbcomp is the tool that compiles .xkb config files into a format used by X11. If this fails due to syntax, file location, or permissions, your graphical session might not start.

How to Debug the Problem

Before applying fixes blindly, let’s figure out where things are breaking.

Check Xorg Logs

Inspect the X server log:

grep -i xkb /var/log/Xorg.0.log

Look for:

(EE) xkbcomp: Can't find file "...”
(EE) Failed to load XKB keymap
(WW) xkbcomp: Errors encountered in keymap file

Run xkbcomp Manually

Test the XKB compiler directly:

xkbcomp $DISPLAY output.xkb

This may help surface the exact error if the server isn’t specific.

Verify File Existence

Ensure the essential directories are present:

ls /usr/share/X11/xkb/

Focus on:

• rules/
• symbols/
• types/

How to Fix xkbcomp and X Server Errors

Here’s a prioritized list of fixes to resolve the issue:

1: Reinstall XKB Data Package

Reinstall the keyboard configuration package for your distro:

• Ubuntu/Debian: sudo apt-get install --reinstall xkb-data
• Fedora/RHEL: sudo dnf reinstall xkeyboard-config
• Arch Linux: sudo pacman -S xkeyboard-config

2: Reset to a Default Layout

Set a clean keyboard layout:

setxkbmap -layout us

If it fails, explicitly provide the path:

setxkbmap -I/usr/share/X11/xkb -layout us

3: Fix File Permissions

Give read access to XKB directories:

sudo chmod -R a+r /usr/share/X11/xkb

4: Remove User-Level Overrides

Sometimes, local files override system defaults and introduce conflicts. Remove them:

mv ~/.Xmodmap ~/.Xmodmap.bak
mv ~/.xkb ~/.xkb.bak

5: Regenerate Xorg Configuration

If the error persists, regenerate the X configuration:

sudo Xorg -configure
sudo mv /root/xorg.conf.new /etc/X11/xorg.conf

This helps reset all X settings, including input devices.

Tips to Prevent Future Errors

To avoid encountering this again:

• Avoid directly editing system XKB files (/usr/share/X11/xkb). Instead, use overrides or tools like setxkbmap.
• Use localectl on systemd-based systems for permanent keyboard layout changes: sudo localectl set-x11-keymap us
• Always test custom keymaps with xkbcomp before applying them permanently.

Conclusion

The “xkbcomp” errors in X11 aren’t always fatal, but when followed by “xinit: connection to X server lost,” they indicate a severe misconfiguration that may crash the graphical environment.

By:

• Reinstalling xkb-data or xkeyboard-config
• Fixing permissions
• Resetting to default layout
• Removing conflicting configs

…you can restore your desktop session reliably.

Would you like an extended guide on custom XKB layouts or remapping keys safely using .xkb overlays or xmodmap? Let me know in the comment section.