I've just published https://pypi.org/project/twisted-iocpsupport/1.0.2rc0/ for 3.10 wheels (with no actual code changes) it should be compatible with python 3.6-3.9 on Twisted>=21.2.0 and py3.6-3.10 on Twisted>=21.7.0 You can install with: python.exe -m pip install Twisted-iocpsupport==1.0.2rc0 or: python.exe -m pip install 'Twisted @ https://github.com/twisted/twisted/archive/1da2a3e6094ba37593bdef837ae01ba3f...' and choosing to specifically use the IOCP reactor: https://docs.twistedmatrix.com/en/latest/core/howto/choosing-reactor.html#in...