Preparing for Fjord Breaking Changes

This page outlines breaking changes related to the Fjord network upgrade for wallets and front-end developers, chain operators, and node operators. If you experience difficulty at any stage of this process, please reach out to developer support (opens in a new tab).

What's Included in Fjord

The Fjord network upgrade (opens in a new tab) includes the following:

• RIP-7212 (opens in a new tab): Precompile for secp256r1 Curve Support, to reduce gas costs of many smart wallet applications.
• Brotli (opens in a new tab) as a channel compression option, for ~5-15% lower data availability costs.
• Parameter changes:
  • Max sequencer drift (opens in a new tab) becomes a constant with value increased to 1800 seconds
  • 10x increased values for MAX_RLP_BYTES_PER_CHANNEL and MAX_CHANNEL_BANK_SIZE (spec (opens in a new tab))
• The Fjord hardfork activation block (opens in a new tab) includes several transactions to perform all L2 contract deployments, upgrades, enablements, and proxy updates.
• L1 Gas Cost changes:
  • FastLZ (opens in a new tab) based L1 fee cost calculation (opens in a new tab) with an upgraded GasPriceOracle L2 predeploy (opens in a new tab) to compute it
  • GasPriceOracle gets a new function getL1FeeUpperBound as a cheap new way to calculate an upper bound for the max fee of a new transaction
  • getL1GasUsed method of the GasPriceOracle contract (spec (opens in a new tab)) is being deprecated
  • L1GasUsed field of the transaction receipt (spec (opens in a new tab)) is being deprecated

For Wallets and Front-End Developers

The proposed Fjord upgrade to the OP Stack and OP Mainnet changes the formula for estimating the L1 Data Fee component of the OP Stack Transaction Fee.

• getL1Fee on the GasPriceOracle contract (opens in a new tab) has been updated. It now performs FastLZ compression on-chain, which is a better approximation of the compressibility of a transaction. Combined with a linear regression model, this gives a more accurate prediction of L1 data fees.
• getL1GasUsed and the corresponding L1GasUsed field of transaction receipts are being deprecated as they no longer accurately reflect gas usage as of Ecotone. The function and field will remain; however, their usefulness is limited as they still assume calldata batching. getL1Fee should be used when trying to predict L1 Data fees.
• getL1FeeUpperBound is a new method to estimate fee upper bounds when sending transactions. It is much cheaper, in gas costs, than previous methods. This is what wallets and front-ends should use in practice in most cases.
• Read the Fjord Formula section of the Transaction Fees page for more information about the new formula.

Your application may need to be updated to account for this change. Read below to learn how specific changes in the Fjord upgrade require updates to your application.

Preparing Your Wallet or Front-End

Changes to the L1 Data Fee formula may affect your application if you are computing this fee component on your own. It's strongly recommended that you use existing tooling to estimate transaction fees instead of computing them yourself.

• If you cannot use existing tooling, use the getL1Fee function on the GasPriceOracle smart contract to compute the L1 Data Fee component of the transaction fee. Avoid implementing the formula yourself, as it may change in the future.
• Alternatively, you should consider using getL1FeeUpperBound if you only need to estimate an upper bound of the L1 fee for the purpose of transaction sending.

For Chain Operators

The proposed Fjord upgrade impacts OP chains and requires chain operators to upgrade their chain and configure the sequencer for Fjord.

• Max sequencer drift (opens in a new tab) becomes a constant with value increased to 1800 seconds. This gives chain operators more time to respond to L1 node issues without facing a potential L2 chain halt.
• Brotli (opens in a new tab) is now supported as a channel compression option, for ~5-15% lower data availability costs.
• An update of the fee scalars on the SystemConfig is necessary, similar to Ecotone.

--compression-algo value (default: zlib) ($OP_BATCHER_COMPRESSION_ALGO)
The compression algorithm to use. Valid options: zlib, brotli, brotli-9,
brotli-10, brotli-11

For Node Operators

Node operators will need to upgrade to Fjord before the activation date. For Sepolia, the op-node release v1.7.7 (opens in a new tab) and op-geth release v1.101315.2 (opens in a new tab) contain these changes.

These following steps are necessary for EVERY node operator: