The Fault Proofs upgrade is a change that many Superchain and OP Stack chains (OP Mainnet, Base, World Chain, Zora, etc) have either already gone through or will need to go through.

When a chain is upgraded to support fault proofs, the underlying proof submission mechanism changes, invalidating any currently inflight and proven but not finalized withdrawals.

After the upgrade is live, you will be able to prove and finalize withdrawals as normal. If a withdrawal was proven but not finalized before the upgrade, it will need to be reproven.

Superbridge does everything it can to prevent users initiating withdrawals that will be delayed or submitting prove operations that will be invalidated, but sometimes we only learn of chain upgrades a few days before they happen.