When I open IDLE, it opens the window, but then shows a pop-up saying “IDLE’s subprocess didn’t make connection. Either IDLE can’t start a subprocess or personal firewall software is blocking the connection.” I tried restarting my computer (I’m running python on linux), but it still isn’t working.
What command are you giving to launch IDLE?
You might try:
python3 -m idlelib
and see if you get the same error.