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EIP-1559 Support

EIP-1559 is a new upgrade to the Ethereum network that changes how you pay for transactions. It introduces a base fee that varies depending on the network demand, and a priority fee that you can set to get faster confirmation. The base fee is burned, while the priority fee goes to the miner who includes your transaction in a block. Flashbots, starting from mev-geth v1.10.5-mev-0.3.0, has integrated support for EIP-1559 transactions.

While users of the legacy transaction type don't need to make any configuration changes, they should be aware that it's now mandatory to include a gasPrice that is at least equal to the base fee. Coinbase transfer can still be used to incentivize faster inclusion, but it cannot be used to bypass the base fee requirement.

Legacy Transaction example​

Below is an example of signing bundles with a legacy transaction:

const signedTransactions = await flashbotsProvider.signBundle([
  {
    signer: authSigner,
    transaction: {
      to: "0xf1a54b075fb71768ac31b33fd7c61ad8f9f7dd18",
      gasPrice: 10,
      gasLimit: 33000,
      chainId: 5,
      value: 0,
    },
  },
]);

The full amount of gasPrice will be consumed first to clear the base fee, and the remaining will be used as priority fee.

EIP-1559 Transaction example​

Below is an example of signing bundles with EIP-1559 transactions (note: chainId is a required attribute for 1559 or type2 transaction):

const block = await provider.getBlock("latest");
const maxBaseFeeInFutureBlock =
  FlashbotsBundleProvider.getMaxBaseFeeInFutureBlock(block.baseFeePerGas, 1);
const priorityFee = BigNumber.from(2).pow(9);
const signedTransactions = await flashbotsProvider.signBundle([
  {
    signer: authSigner,
    transaction: {
      to: "0xf1a54b075fb71768ac31b33fd7c61ad8f9f7dd18",
      type: 2,
      maxFeePerGas: priorityFee.add(maxBaseFeeInFutureBlock),
      maxPriorityFeePerGas: priorityFee,
      gasLimit: 33000,
      chainId: 5,
      value: 0,
    },
  },
]);

Here the priorityFee is set to 2 Gwei, and the maxFeePerGas is set to be exactly equal to the max base fee in the next block plus the priority fee.

FAQ​

Can a transaction specify maxFeePerGas=0?​

No, all transactions must have maxFeePerGas greater than or equal to block.baseFeePerGas, or they are not eligible for inclusion in a block.

Can a transaction specify maxPriorityFeePerGas=0​

Absolutely, although the builder will need some incentive to include this transaction. With a Flashbots bundle, you can incentivize a builder/validator to include your transactions with block.coinbase.transfer() payments OR via maxPriorityFeePerGas. You can also use both at the same time; the incentive is cumulative.

Will reverting transactions still be discarded?​

Flashbots still uses the same reverting transactions logic after EIP-1559: unless specified in revertingTxHashes in eth_sendBundle, a transaction that reverts invalidates an entire bundle and will not appear on chain.

However, with the new requirement for searchers to provide a gas price that meets the base fee for each transaction, successfully included bundle transactions may end up in the mempool following block re-organizations. If gasPrice=0 is used, re-organized transactions are swiftly dropped from the gossip network, making it unlikely for them to appear in a future block unless reintroduced by another searcher. Transactions that pay at least the base fee will remain in the mempool and have a higher chance of appearing in future blocks, potentially conflicting with expectations regarding reverting transactions.

How can I send a transaction from an account with 0 ETH, like one with a malicious sweeper running against it?​

We have a working example of how to accomplish this in our Sponsored Transaction Github Repository, which has been updated to work with EIP-1559.

Where can I learn more about EIP-1559?​

EIP-1559 Hackmd Cheat Sheet