As others have said, Catalina and above lock down the system folders. That's probably the root cause of your errors. There's a way around it but best to leave them alone. Rather than using homebrew, try compiling from source to a non-system folder, i.e., /usr/local, or even somewhere in your user $HOME folder. You can use xCode, or compile GNU make if you'd rather not use a GUI. Most 'nix apps compile just fine on a Mac. So far as homebrew goes, it's OK, but learning to compile your own apps will give the best reward and you'll have a better understanding of what's actually entailed in creating an app. You're also able to update to the latest versions (OpenSSL, PHP, Apache, etc.) as they come out. FWIW, I'm running 3.10.0 on 10.15.7 using venv's. There are some issues with the latest curties (bpython wants 0.3.5 but I've yet to get it to install so am still on 0.3.4), but that's the fun of rolling your own. BTW, if you use terminal at all, get iTerm. Like bpython, it's awesome.