Imgui stopped working on Ubuntu 20.04.4 LTS

Latest commit on May 9 (60f962) - “Release - label v4 BETA-6” imgui do not start on Ubuntu 20.04 (Focal Fossa) anymore. It worked “some” commits before…

[API] [INFO ] : Initialising Daemon
sonic-pi-imgui: /home/mikael/work/sonic-pi/app/gui/imgui/core/imgui_draw.cpp:1978: ImFont* ImFontAtlas::AddFontFromFileTTF(const char*, float, const ImFontConfig*, const ImWchar*): Assertion `(0) && "Could not load font file!"' failed.

I guess it assumes some font now that was not needed before? Any chance of having some fallback?
(Qt version do not build on 20.04 as it’s default Qt library is too old, but I am perfectly fine with that for the moment)


The core team encourage to use the github repo and open an issue rather to use this forum for this kind of topic.



Yes, please do use the Github issue tracker for development issues: Issues · sonic-pi-net/sonic-pi (

Also, please note that the IMGUI-based GUI isn’t fully-featured or supported at this stage. It’s there mainly as an alternative secondary interface to our C++ GUI library to ensure it is portable and not specifically tied to our (supported) Qt based GUI.

With respect to Qt, Sonic Pi should compile against both the latest 5.x and 6.x branches.

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Ubuntu 20.04 does not have the latest Qt 5.x but it will probably work once I upgrade to (k)ubuntu 22.04 LTS (eventually). Meantime IMGUI is good enough for me :slight_smile:
I will create a ticket in github issue tracker.

Yup I have latest SP built from source running on 22.04 LTS using Qt6



Does the linux readme on the repo still ok ?

It should be accurate. Please do create an issue if something doesn’t work as expected.