Bitcoin experienced another brief blockchain reorganization on September 11. According to Galaxy Research, SpiderPool's block was initially seen by its nodes, but AntPool subsequently produced a valid block at the same height, which ultimately became part of the main chain.
Two versions of blocks appear at the same height
Galaxy records show that AntPool's winning block had a height of 966,500, a timestamp of 11:30:30 UTC, and contained 4,359 transactions. SpiderPool also generated a valid block at the same height.
Nodes see different versions in sequence
Since Bitcoin blocks are not simultaneously broadcast to every machine on the network, Galaxy's node first saw the SpiderPool version, then later discovered that AntPool continued mining at the same height. Following Bitcoin’s rule of selecting the longest valid chain based on cumulative proof-of-work, the node eventually switched to the AntPool branch.
Three occurrences have taken place in the past month.
Galaxy Research also noted that block reorganizations occurred on August 16 and August 24 at heights 962,722 and 963,853, respectively. The firm stated that such single-block reorganizations are typically not uncommon and do not indicate a network failure.