We have an issue in Symfony Process for a long time : Process::start is blocking on Windows.
It's a tricky issue and it would be awesome that we could fix this. I've proposed a patch, unfortunately it seems it does not solve the issue on all setups.
I got three different Windows implementations for Symfony/Process on Windows platform. All of them are working for me and solve the bug, but it seems some of them are failing on some installs.
I need help and if you can run the Process test suite and give feedback with the following template in this gist comments: