As I know that there is no competition for mining new blocks in POA blockchain as each node mines new block at its given time slot. I have a parity PoA blockchain setup with 5 nodes. While examining the blockchain, I can see some blocks with Uncle blocks.

Why are there uncle blocks in PoA blockchain?

1 Answer 1


Clique consensus can actually produce forks and therefore have Uncle blocks as mentioned here: How does the Clique PoA consensus protocol choose the next block-minting node?

  • Although there are forks in clique, uncle blocks are not part of the consensus rules. In the clique EIP the uncle list is explicitely set to an empty list.
    – Ismael
    Mar 5, 2019 at 16:51

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