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Title: From Mozc/IBus initialization failure to AppArmor enfocing profiles delayed deployment
License: CC-BY-4.0
Author: https://mememodoki.jp
Date: 2026-09-23
---

# Linux Troubleshooting Case Report

## Through Mozc/IBus initialize failure to AppArmor enforce profiles

Whenever you hit silent failure, doubt IPC/Locking contamination,
improper MAC (such as SELinux, AppArmor) settings, and disk capacity.

## Case report: A new user cannot use Mozc/IBus while existing old users can.

A working GNU/Linux GNOME machine with Mozc/IBus Japanese input encountered a confusing `mozc_server` launch failure with a new user. Standard diagnosis such as config file, IPC, and Locking did not solve the issue.

Comparison with old users status showed improper AppArmor profile settings. Since the AppArmor profiles creation was delayed, initial users Mozc, IBus related files were successfully created. After Mozc and IBus profiles got enforce mode, their Mozc/IBus still worked because the profiles had permission for non-initial runtime paths. The new user, on the other hand, failed to create initial Mozc/IBus directories and files, because the profiles lacked such initial launch specific permissions. Furthermore, after AppArmor profile adjustments, the troubled user desktop suffered from D-Bus session bus contamination, which resulted in incapability on specific applications (in this case, Firefox ESR) until the new desktop session restarted.

This kind of trouble does not occur for major GNU/Linux Desktop usage. Combination of user creation, AppArmor profile creation and enforce mode deployment delay, caused confusing, silent failure, which is hard to solve under normal troubleshooting guidelines. Disk space and/or inode exhaustion can cause silent failures, too.

**Key Takeaway:** Whenever you meet a silent, unknown failure, doubt MAC setting, IPC contaminations, and disk capacity.