2 mined blocks at the same time on Bitcoin

Breathe and breathe, Bitcoin works as expected

2 blocks for the price of one – The Bitcoin network (BTC) has just experienced a rare phenomenon: a stale block. This happens when the same block height is validated at the same time by 2 minors. No need to panic though! It has already happened and the Bitcoin code knows how to proceed in this case.

A statistical improbability that hasn’t happened for a year.

Chance is sometimes mischievous, and a rare event has just happened again almost exactly one year after the previous one. It is the Fork Monitor tool, proposed by BitMEX Research, which has just Bitcoin Up detected a new stale block on Bitcoin’s blockchain, on January 20th.

Precisely at the level of block 666,833, the SlushPool and F2Pool mining pools entered into conflict by validating a block of transactions at the same time.

It is finally the block mined by SlushPool which was kept in the sequence of blocks of the Bitcoin blockchain, the F2Pool block becoming this famous stale block. This „stale block“ phenomenon forces the network to reorganise (reorg), but this statistical misfortune was anticipated and quantified by the creator of Bitcoin.

In short, this stale block was the result of an unfortunate user, anxious to succeed in having a too slow transaction validated using the Replace-By-Fee feature: by submitting the same transaction, while agreeing to pay more fees, one can hope to see this steroid transaction validated first. But this user has submitted a total of three versions of the same transaction.

A small summary of the situation, constructed by 0xB10C.

In the end, and in the middle of this somewhat confusing but perfectly normal situation, SlushPool and F2Pool fought on two different channels (the winner and the loser), while a final version of this transaction just got lost in the void – included… nowhere.

Satoshi Nakamoto’s genius had it all figured out

Andreas Antonopoulos, best known for his book „Mastering Bitcoin“, reminds those who were already starting to scream at the double expense that the phenomenon of reorganisation is quite possible naturally, by pure statistical misfortune.

Thus, in one of his tweets, the author of „Internet of Money“ mentions the eighth page of Sataoshi Nakamoto’s white paper on Bitcoin, published in 2008:

This phenomenon shows that Bitcoin works exactly as expected 12 years ago, exactly as Satoshi describes it (…) when they calculate the probability of a reorganisation after 1 block, 2 blocks… etc.“. (…) »

As a result, it is increasingly unlikely that a reorg can occur beyond an unlucky first stale block. Even for a single block, let’s recall once again that this had previously only happened once in almost a year.

Other good news: the tougher the competition between the miners of the Bitcoin network, the more difficult it becomes to mine, and the less likely it is that a stale block will occur, especially beyond one block.

It should also be noted that more important reorg phenomena can exist on blockchains, such as the one of Craig Wright’s crypto BSV: in 2019, a reorganization of 3 blocks had occurred.