What’s your biggest Unreal Engine ‘oops’ moment?

I put a lot of value in learning from my own mistakes, and I was wondering what mistakes everyone has made that led to big learning moments?

I think my biggest oops moment was in one of my first projects, I reorganized the entire folder structure using my computer’s file browser instead of doing it within Unreal. It broke every reference in the game, and I had to rebuild everything from the ground up. I'll never make that mistake again! 😅

Whats yours?