F2pool Mining Pool Generated an Invalid Bitcoin Block

According to the ForkMonitor node monitoring tool, the Bitcoin (BTC) network produced two blocks with a block height of 783426. The incident, noticed by BitMEX Research, was shared on Twitter a short time ago. This means that there is a temporary fork in the Bitcoin blockchain where two different blocks are mined simultaneously by different miners.

One of them was F2pool, which seemed to produce an invalid block that did not comply with the BIP66 protocol rule. This rule requires that all signatures in the block be strictly DER encoded. The invalid block was ultimately rejected by the network and replaced with another valid block. The reason why F2pool produced an invalid block is still unclear.

F2pool is known as a cryptocurrency mining pool founded in 2013 that supports mining of Bitcoin and more than 40 other coins. According to BitMEX Research, F2pool’s invalid block may have been caused by faulty signature operations, but the exact cause is still being investigated. However, the temporary fork has caused some confusion and instability, especially among Bitcoin users and services that rely on SPV wallets or older versions of Bitcoin Core that do not fully validate blocks.

The consequences of generating an invalid block are the rejection of the block by other nodes following the consensus rules of the Bitcoin network. The miner who produced the invalid block will not receive any reward for it and will have wasted computational power and electricity.

Transactions included in the invalid block will be re-evaluated by other nodes and, if still valid, added back to the transaction pool for inclusion in future blocks. Therefore, generating an invalid block does not harm the network or users, it only harms the miner who produced it.