Bug 520566 - Ubuntu-packaged version of Fcitx ignores modifier keys when using Wayland input-method protocol unless you set a bunch of environment variables
Summary: Ubuntu-packaged version of Fcitx ignores modifier keys when using Wayland inp...
Status: REPORTED
Alias: None
Product: neon
Classification: KDE Neon
Component: Packages User Edition (other bugs)
Version First Reported In: unspecified
Platform: Neon Linux
: NOR normal
Target Milestone: ---
Assignee: Neon Bugs
URL:
Keywords: regression
Depends on:
Blocks:
 
Reported: 2026-05-23 14:40 UTC by deadboy2537
Modified: 2026-06-17 18:45 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
A video testing keyboard input shows that even when the Shift or Caps Lock keys are pressed, the letters typed remain unchanged. (569.60 KB, video/mp4)
2026-05-23 14:40 UTC, deadboy2537
Details

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Description deadboy2537 2026-05-23 14:40:27 UTC
Created attachment 192566 [details]
A video testing keyboard input shows that even when the Shift or Caps Lock keys are pressed, the letters typed remain unchanged.

DESCRIPTION
When using fcitx5 under Plasma Wayland session, keyboard modifier keys (Shift/Caps Lock) fail to work correctly in pure Wayland applications. Pressing Shift + Letter or Caps Lock + Letter only outputs lowercase letters, and pressing Shift + Number keys fails to output symbols.

STEPS TO REPRODUCE
1. Log into a KDE Plasma Wayland session.
2. Ensure Fcitx5 is set as the Virtual Keyboard in System Settings.
3. Launch Fcitx5 and open a native Wayland application (e.g., Konsole).
4. Switch to the Fcitx5 English keyboard layout (Keyboard - English).
5. Attempt to type uppercase letters using Shift or Caps Lock, or attempt to type symbols using Shift + Number row keys.

OBSERVED RESULT
Modifiers seem to be ignored. 
- Typing `Shift + A` outputs `a`.
- Turning on Caps Lock and typing `A` outputs `a`.
- Typing `Shift + 1` outputs `1` instead of `!`.

EXPECTED RESULT
Modifier keys should work as expected, outputting uppercase letters and symbols.

SOFTWARE/OS VERSIONS
Operating System: KDE neon (Testing/Unstable)
KDE Plasma Version: 6.6.90
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
Architecture: Aarch64

ADDITIONAL INFORMATION
1. When switching to other input methods within fcitx5, such as Pinyin, typing uppercase letters works, but typing symbols using `Shift + Number keys` still fails.
2. Workaround observation: If I force-set `GTK_IM_MODULE=fcitx`, `QT_IM_MODULE=fcitx`, and `XMODIFIERS=@im=fcitx` variables in `/etc/environment`, the Shift/Caps Lock keys work perfectly fine in Wayland apps. Although doing so would cause a visual bugs.
Comment 1 Link 2026-06-17 02:21:27 UTC
Can reproduce, just started happening today after I update.

Operating System: KDE neon User Edition
KDE Plasma Version: 6.7.0
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
Kernel Version: 6.17.0-35-generic (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 7640U w/ Radeon 760M Graphics
Memory: 32 GiB of RAM (27.2 GiB usable)
Graphics Processor: AMD Radeon 760M Graphics
Comment 2 Nate Graham 2026-06-17 12:25:06 UTC
Cannot reproduce on KDE Linux with Fcitx5 set up according to the instructions at https://linux.kde.org/docs/cjkv-input/ (i.e. using Flatpak). and testing on https://keyboard.afjs.dev.

Does the issue happen if you uninstall Fcitx from system packages and try the Flatpaks according to the instructions I linked to? Even though they were written for KDE Linux, they should work for KDE neon too.
Comment 3 Link 2026-06-17 13:43:24 UTC
For me, uninstalling the ubuntu-noble-universe Fcitx5 and installing Flathub fcitx5 and the issue is gone, I can type capital letters and symbols now! 🥳

This has drove me crazy, Thank you Nate! ♥️

I'm not sure which one Discover defaults too, so I think the docs should be updated to mention installing the Flathub Fcitx5 instead of the ubuntu-noble-universe one though 😄
Comment 4 Nate Graham 2026-06-17 18:45:05 UTC
That's great news!

It sounds like there may be a problem with the way Fcitx is packaged or integrated in Ubuntu (the base of KDE neon), or the version may simply be too old to work well; it's over 2 years old at this point. That's unfortunate.

The documentation I linked to is targeted at users of KDE Linux, which uses Flathub as the exclusive source of 3rd-party software in Discover, so recommending to use Flathub is not necessary there.

Other distros will have to document the supported way to get Fcitx according to how they have things set up.