What Is Stale Block?

A stale block is a block that was mined successfully but didn't make it onto the current longest blockchain, usually because another block at the same height got added first.

Get to Know with Stale Block

A stale block is like a runner-up in a race. It's a block that miners worked hard to mine, but it didn't make it onto the main blockchain. This can happen if another block is added to the chain faster. When this occurs, it causes a temporary split in the network, with two competing blockchains.

Miners Fix

Miners fix this split by continuing to mine new blocks. Eventually, one chain becomes the winner, and miners switch to following that chain. The stale block is now left behind, considered invalid. Any reward attached to it also becomes useless and can't be spent. The transactions from the stale block go back to the mempool to be included in future blocks.

What Causes Stale Block?

Stale block are rare in Bitcoin because of the fast communication between mining pools. However, they can still happen due to network delays. When a miner in one part of the world finds a block, it takes time for that information to reach other miners globally. During this time, another miner might find the same solution.

For Example

Imagine one miner in North America and another in Australia both finding a block simultaneously. They broadcast their findings to nearby nodes, causing a stale block situation. Eventually, the network agrees on the longest chain, and the stale block transactions return to the mempool.

Stale Blocks on Ethereum and Others

Before Ethereum's move to proof-of-stake, stale blocks, known as "uncle blocks," were possible. Miners could still earn a reward from them, although less than usual. Other proof-of-work chains also experience stale blocks, but they're more common than in Bitcoin.

Also Read

What are Block Rewards?

What Is Mining Reward?

What is a Cryptographic Hash Function?

DISCLAIMER: This article is informational in nature and is not an offer or invitation to sell or buy any crypto assets. Trading crypto assets is a high-risk activity. Crypto asset prices are volatile, where prices can change significantly from time to time and Bittime is not responsible for changes in fluctuations in crypto asset exchange rates.