@archie3d It uses the system libsdl2-dev from the ubuntu-sdk-20.04 clickable framework and for that framework the SDL2 package is 2.0.10+dfsg1-3 on Focal/arm64 ...i tend to find even if your building for a newer version of UT you still have to use older packages because there is a break it seems in the versions and packaging being updated? ..idk i do know every time i try to build with newer repos something breaks ....