Emacs Command of the Day offers a tip that, oddly, a lot of people don’t seem to know about:
ESC ESC ESC (which is keyboard-escape-quit) is an Emacs superpower!
It's a more general version of yesterday's command. It exits recursive editing, deactivates the region, closes split windows, and my personal favourite: it closes active minibuffers! pic.twitter.com/tOEb2dOrQh
— Ⓔ Command of the Day (@ecotd) July 2, 2018
I usually use it after trying Ctrl+g and right before sending a SIGUSR2 signal.
I didn’t realize the part about closing the minibuffer but that’s probably why it often works for me.