You actually can back up, but it is time-consuming and not easy to discover. You need to manually step through the project tree until you find the first feature that is incorrect (this is not necessarily the first feature that fails to compute!), then either fix the sketch itself, or fix the sketch attachment, or the fillet/chamfer edges in the case of fillets/chamfers, and then proceed down the tree until it's all correct.

It's a lot of work, but often less work than starting from scratch.