XFormers is now needed for the flux region spatial control to work.

Go to your python_embeded folder and Check your pytorch and cuda version:

python.exe -c "import torch; print(torch.__version__)"

check for xformers if installed:

python.exe -m pip show xformers

Please go to: https://github.com/facebookresearch/xformers/releases

Check for the latest Xformers version that is compatible with your installed Pytorch version.

You can Install the latest version of xformers using this command:

python.exe -m pip install xformers==PUTVERSIONHERE --index-url https://download.pytorch.org/whl/cuVERSION

example For PyTorch 2.5.1 with CUDA 12.4:
python.exe -m pip install xformers==0.0.28.post3 --index-url https://download.pytorch.org/whl/cu124

As of 8th December 2024:
Recommended:
xformers==0.0.28.post3
PyTorch 2.5.1
CUDA version: cu124 (for CUDA 12.4)