how to find the UE_PYTHON_DIR environment variable?

Hi, I am a beginner in using unreal engine(4.25). I am trying to use python in my project but I found that the version of the python plugin is 2.7. The unreal document told me that I can change the version of python by setting the UE_PYTHON_DIR environment variable but I am confused as I can’t find this variable. Can anyone teach me how to find the UE_PYTHON_DIR environment variable in detail?

The environment variable is within the operating system, not UE, and you’ll need to create it. You can find tutorials online if you don’t know how to set an environment variable. You would set the path to where ever your python is installed, like F:\Python39. Afterward, I believe you have rebuild the engine.

By the way, v4.26 automatically uses python 3.7.7. So if you just want to use python 3, using 4.26 may be easier for you.

Ok, thanks for letting me know.