Public Bitcoin mining firm Marathon Digital encountered a setback on Wednesday when it mined an invalid Bitcoin block, resulting in a loss of potential earnings. The invalid block was identified by Bitcoin users and developers, including Casa CTO Jameson Lopp, who observed the issue using their own Bitcoin nodes.
An invalid block is one that violates Bitcoin’s consensus rules, making it unacceptable to network nodes. Various entities, including miners, exchanges, and ordinary users, run these nodes to maintain their own copies of the blockchain and validate new blocks of transactions. Reasons for labeling a block as invalid can range from including double-spend transactions to exceeding Bitcoin’s block size limit. While Marathon did not specify why their block was invalid, some observers suggested it may have been due to a transaction ordering problem.
Marathon Digital confirmed their responsibility for the invalid block after the issue came to light. In response to Decrypt’s inquiry, a Marathon spokesperson acknowledged that this error was unprecedented for the company and considered it an anomaly. They emphasized that the problem did not stem from a flaw in Bitcoin’s protocol but rather from an unanticipated bug arising from one of their experiments.
Marathon routinely conducts experiments utilizing a small portion of its hash rate to optimize operations. The firm explained to X (Twitter) that the invalid block resulted from a bug that emerged during one of these experiments. As soon as the problem was detected, Marathon promptly rectified the error.
Following the revelation of the problematic block, Marathon’s shares on Nasdaq, where it trades under the ticker MARA, experienced a 2.9% decrease for the day. BitMEX Research commented on the situation, suggesting that the block had transactions in the wrong order. Specifically, a transaction (A) spent from an output of another transaction within the same block (B), but txin B was included after txin A. Consequently, the block was rendered invalid.
While Marathon may have encountered a setback with this invalid block, the incident highlights the importance of vigilance and adherence to Bitcoin’s consensus rules. It also underscores the ongoing experimentation and optimization efforts within the Bitcoin mining industry, as companies like Marathon seek novel ways to enhance their operations.
