Bitcoin Miner Marathon Confirms Mining Invalid BTC Block Due to a Bug

Bitcoin mining company Marathon Digital (MARA) has mined an invalid Bitcoin block at height 809478, according to several developers, miners and researchers.

The miner confirmed the mining of the invalid block on social media platform X (formerly Twitter), citing a bug during an experiment. "We utilize a small portion of our hash rate to experiment with our development pool and research potential methods to optimize our operations," Marathon said. "The error was the result of an unanticipated bug that came from one of our experiments," the company added.

Earlier Wednesday, anonymous Bitcoin developer "0xB10C" wrote on X that MaraPool had a "transaction ordering issue," which was confirmed by CasaHODL co-founder Jameson Lopp.

The invalid Bitcoin block was rejected by other node operators. The block contained a transaction that was ordered incorrectly with a spending output transaction, thus, the block was invalidated, according to BitMEX Research.

The mining of invalid block raised some questions within the community as to the security of the network. However, the rejection of the block was cited by Marathon as an example of the resilience of the Bitcoin network.

"In no way was this experiment an attempt to alter Bitcoin Core in any way," the miner said, adding that the incident was unintended but "underscores the robust security of the Bitcoin network, which rejected and rectified the anomaly."

The miner's shares were down nearly 2% on Wednesday, while peer Riot Platform (RIOT) was down about 0.7%, and bitcoin price was mostly positive.

UPDATE: (Sept. 27, 16:56 UTC): Updates throughout to add confirmation by Marathon and comments from the company.