Optimistic Ethereum Fixes June 2021 Deposit Bug

Optimistic Ethereum’s June 2021 testnet bug blocked L1 ⇒ L2 deposits by stalling on deposit 2500. The data transport layer (DTL) lacked this deposit’s record, halting L2 geth’s execution. The team traced the issue via logs and API queries. Resetting the production DTL restored functionality. The root cause remains unclear, possibly a Kovan reorg. Author: Kelvin Fichter.