I once had an incredibly frustrating experience trying to upgrade major dependencies due to poorly maintained Create React App v4 template code which hid away important details that had OpenSSL security issues in the current version, while v5 had an enormous amount of backwards compatibility breaking.

https://www.freecodecamp.org/news/how-to-upgrade-node-and-jest-while-on-react-scripts-v4/

There was absolutely no good resource for navigating all of this, so I wrote a guide for that and added links to basically everything helpful I found on the way. Luckily Facebook has now officially stopped recommending CRA, but there’s so many years of React applications created using this that will need this kind of guide to break out and make basic upgrades.