A Deep Dive into the Recent BCH Hard Fork Incident By Mark Nesbitt , Peter Kacherginsky , and Don Yu On May 15th, Coinbase detected a depth-2 chain reorganization on the Bitcoin Cash blockchain. The reorg targeted BCH funds that were erroneously sent to BTC segwit addresses, which were previously unspendable but became recoverable as part of the May 15 BCH upgrade. Based on publicly available data, the reorg was caused by a hashpower struggle between two miners, the outcome of which was $1.39M (3655 BCH) being sent to the originally intended recipients and $82k (216 BCH) being sent to unknown addresses. I. Double Spends on BCH Twice a year, the Bitcoin Cash (BCH) network hard forks as part of scheduled protocol upgrades. The most recent upgrade occurred on Wednesday, May 15 at 5:00am PT (12pm GMT) and included the following two main changes : Enable Schnorr signatures . Schnorr signatures are a cryptographic signature system that enables scaling solutions that are part of the BCH roadmap.