Juniors I know all need to focus on the error message: read it, understand it, and then apply the scientific method : formulate one hypothesis, test it, analyse results, rince and repeat. Each experiment should other a path to what's next.

They are also forbidden to stay stuck more than one hour without requesting feedback(actually that's a rule for everyone on my team).

Pairing with seniors is a great way to learn too, you'll discover tons about what makes your company's code special.

You can block stackoverflow.com, or at the very least avoid searching on it before having tried to __understand__, not solve, the issue.