Perfect example for me is that I use beancount for tracking my finances. It broke one day because I tried upgrading some dependencies from v2 to v3. I tried messing around with the imports and some function names but it didn't help and after wasting 30m I decided to give up on the upgrade.

2 weeks later when I wasn't busy trying to get it to work, I gave it another shot. This time went so much more smoothly and now everything works (fingers crossed since I haven't actually tried out ALL the functionality).