Bitcoin experienced a normal one-block blockchain reorganization on Sept. 11 at height 966,500 after SpiderPool and AntPool produced competing valid blocks on the same parent. Galaxy Research’s node received SpiderPool’s block first, temporarily treating it as the chain tip, while AntPool’s version later became canonical after AntPool mined block 966,501 on top of it. Bitcoin nodes select the valid chain with the greatest accumulated proof-of-work (computational work securing the network), so Galaxy’s node switched branches and SpiderPool’s block became stale, or orphaned. Galaxy said AntPool’s winning block carried a timestamp of 11:30:30 UTC and included 4,359 transactions. SpiderPool’s discarded block contained a reward of roughly 3.1389 BTC that became unusable, compared with about 3.1411 BTC earned by AntPool. The event was the third one-block reorganization in less than a month, following incidents at heights 962,722 on Aug. 16 and 963,853 on Aug. 24. Such short-lived competing blocks are generally considered normal and were not caused by a network fault, consensus bug or successful attack.