# Input Method Cannot Be Activated in Packaged Slicer on Ubuntu

**URL:** <https://discourse.slicer.org/t/input-method-cannot-be-activated-in-packaged-slicer-on-ubuntu/42958>\
**Category:** Support\
**Tags:** python\
**Created:** [May 16, 2025, 6:28am UTC](https://discourse.slicer.org/t/input-method-cannot-be-activated-in-packaged-slicer-on-ubuntu/42958 "2025-05-16T06:28:20Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![herryliq](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@herryliq](https://discourse.slicer.org/u/herryliq)\
**Post date:** [May 16, 2025, 6:28am UTC](https://discourse.slicer.org/t/input-method-cannot-be-activated-in-packaged-slicer-on-ubuntu/42958/1 "2025-05-16T06:28:20Z")

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We encountered an input method issue during custom development based on **3D Slicer 5.6.2**.

- **Operating System** : Ubuntu 22.04.4 LTS

- **Slicer Version** : 5.6.2 (custom build)

#### Problem Description:

- When running Slicer directly from the **build environment** (compiled from source), the **system input method (e.g., ibus, fcitx)** works correctly in text fields.

- However, when running **Slicer from the packaged version** (generated using `cpack`), it becomes **impossible to activate the system input method** in any text input field.

- This issue only occurs on **Ubuntu**. On **Windows 11** , the packaged Slicer can activate and use the input method without any problems.

#### Initial Thoughts:

This might be caused by:

- Missing Qt platform input context plugins in the packaged environment (e.g., `libqt5gui5-plugins`, `qtvirtualkeyboard`, or `platforminputcontexts`).

- Environment variables such as `QT_IM_MODULE`, `QT_PLUGIN_PATH`, or others not being set correctly in the packaged runtime.

- Differences in runtime plugin loading between build and installed environments.

* * *

We’d appreciate any guidance or suggestions from the Slicer developer community on how to resolve this issue.

Is there a recommended way to ensure that input method support (e.g., ibus) is preserved in the packaged Slicer on Linux?

Thanks in advance!

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [May 16, 2025, 12:06pm UTC](https://discourse.slicer.org/t/input-method-cannot-be-activated-in-packaged-slicer-on-ubuntu/42958/2 "2025-05-16T12:06:40Z")

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Thanks for reporting this. Since you already have a way to reproduce this problem, the best would be if you could investigage this a bit further. First of all, test how Slicer behaves when you build it but not run it from the build tree, but create a package and use that. If your packaged/installed Slicer has the same issues with system input method switches then you can test all your theories (missing Qt plugins is the most likely).

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**Author:** ![herryliq](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@herryliq](https://discourse.slicer.org/u/herryliq)\
**Post date:** [May 20, 2025, 4:21am UTC](https://discourse.slicer.org/t/input-method-cannot-be-activated-in-packaged-slicer-on-ubuntu/42958/3 "2025-05-20T04:21:09Z")

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Thank you for your feedback. I would like to ask whether anyone has reported a similar issue and if there is already a solution in the community.  
If no one has reported this issue yet, I will complete the final investigation and confirmation, and provide the modification plan here.

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [May 20, 2025, 5:09am UTC](https://discourse.slicer.org/t/input-method-cannot-be-activated-in-packaged-slicer-on-ubuntu/42958/4 "2025-05-20T05:09:59Z")

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> [@herryliq](#):
>
> would like to ask whether anyone has reported a similar issue and if there is already a solution in the community

I don’t recall anybody reporting related problems but you have a look at the list of known issues in the [issue tracker](https://github.com/Slicer/Slicer/issues).

> [@herryliq](#):
>
> If no one has reported this issue yet, I will complete the final investigation and confirmation

Probaly right now you are more interested in this topic than anyone else, so I would encourage you to investigate and try to fix issues that you find.