fromRLPSerializedBlock throws "invalid block. More values=20 than expected were received (at most 5)" following Cancun activation

[solimander]

Block.fromRLPSerializedBlock throws invalid block. More values=20 than expected were received (at most 5) when providing a Goerli block following the activation of the Cancun hardfork.

Repro:

import { Chain, Common, Hardfork } from '@ethereumjs/common';
import { Block } from '@ethereumjs/block';

const common = new Common({ chain: Chain.Goerli, hardfork: Hardfork.Cancun });

const run = async () => {
  const providerURL = 'https://goerli.infura.io/v3/your-infura-key';
  const block = await Block.fromJsonRpcProvider(providerURL, 10507619n, {
    common
  });

  const headerRLP = block.header.serialize();
  const blockFromHeader = Block.fromRLPSerializedBlock(headerRLP, { common });
  console.log({ blockFromHeader });
};
run();

[jochem-brouwer]

Yes, you are trying to import RLP fields of a BlockHeader into a Block, which does not work. This works:

import { Chain, Common, Hardfork } from '@ethereumjs/common';
import { Block, BlockHeader } from '@ethereumjs/block';

const common = new Common({ chain: Chain.Goerli, hardfork: Hardfork.Cancun });

const run = async () => {
  const providerURL = 'https://goerli.infura.io/v3/your-infura-key';
  const block = await Block.fromJsonRpcProvider(providerURL, 10507619n, {
    common
  });

  const headerRLP = block.header.serialize();
  const blockFromHeader = BlockHeader.fromRLPSerializedHeader(headerRLP, { common });
  console.log({ blockFromHeader });
};
run();

I.e. the only change is: const blockFromHeader = BlockHeader.fromRLPSerializedHeader(headerRLP, { common });

[solimander]

Ah, thanks! Totally missed that!