Deprecation of Snowbridge V1
Snowbridge V2 has been running on Polkadot and Ethereum for a year. With V2 available and established, we plan to begin deprecating Snowbridge V1 and move remaining users and parachain integrations to the V2 protocol.
The goal of this post is to explain why V1 is being deprecated, provide historical context for the design decisions made at the time, outline the benefits of retiring V1, and describe the proposed migration and deprecation plan.
Summary
Snowbridge V1 was designed and launched under the constraints available at the time. It provided a simple end-user experience and delivered the first version of trustless Ethereum <> Polkadot asset transfers, but it also required on-chain fee estimation, fixed gas price assumptions, ordered delivery, and operationally managed sovereign account balances.
Snowbridge V2 resolves these issues by moving fee estimation off-chain, using user-provided fees through newer XCM capabilities, supporting unordered message execution, and standardizing fee handling around ETH. V2 is cheaper, more flexible, and better aligned with future Snowbridge development.
We are proposing to deprecate V1 in phases:
- Reduce V1 relaying support by only relaying profitable messages.
- Increase V1 fees to discourage new usage and make relaying sustainable.
- Rebalance fee-paying sovereign accounts from Treasury. This account top-up is required before the increased fees can be supported.
- Close V1 channels after a 90-day migration period.
Background
Snowbridge V2 was announced as live in November 2025 and introduced major improvements over V1, including lower fees, off-chain fee estimation, unordered message execution, arbitrary contract support, and support for richer XCM-based integrations.
V2 also changed the bridge fee model. Instead of relying on rigid on-chain assumptions about gas prices and DOT/ETH exchange rates, V2 allows fees to be estimated off-chain using live pricing data and current Ethereum gas prices. This is more accurate, easier to maintain, and cheaper for users.
With the majority of bridge traffic already moved to V2, continuing to support V1 creates additional operational and security costs while providing limited benefit.
Snowbridge V1 Limitations
Snowbridge V1 has several known limitations:
- On-chain fee calculation.
- On-chain DOT/ETH fee conversion.
- A fixed on-chain Ethereum gas price.
- Ordered delivery.
- Fees are collected into Treasury-controlled accounts, requiring sovereign accounts on Ethereum and Bridge Hub to be topped up in order to pay relayer fees.
These issues make V1 difficult to operate sustainably. In particular, relayers can take a loss when the configured on-chain exchange rate or gas price diverges from market conditions. Ordered delivery also means one underpriced or failing message can block later messages in the queue.
Why V1 Was Released With These Limitations
Snowbridge V1 was released with these tradeoffs because the required protocol and runtime features did not exist yet.
At the time of the V1 release, XCM did not support user-provided fees in the way required by Snowbridge. Fees therefore had to be calculated on-chain. Snowbridge V2 uses the InitiateTransfer XCM instruction, which allows users to offer a fee amount directly in the XCM program.
Asset Hub also did not support asset swaps at the time. This meant fees had to be collected into sovereign accounts, and those accounts needed to be balanced and topped up across the bridge. In V2, the fee asset is standardized to ETH on both sides of the bridge. There are no on-chain DOT/ETH conversions. Instead, prices are calculated off-chain in real time using the current Asset Hub liquidity pool price and current Ethereum gas prices.
Even with these limitations, V1 delivered an end product that was simple for end users to understand and use. The design made sense given the capabilities available at the time, but those constraints no longer apply.
Benefits of Deprecating V1
Deprecating V1 has several benefits:
- Security: maintaining both V1 and V2 doubles the number of protocol paths that need to be reviewed, monitored, and defended.
- Less operations and infrastructure: retiring V1 removes the need to operate and maintain two versions of the bridge protocol.
- Faster future development: new features often require careful consideration of the V1 code path. This makes features such as circuit breakers harder and more cumbersome to implement.
- Better sustainability: Snowbridge was positioned as a common good product, but relaying V1 messages at a loss is not sustainable.
The bridge should converge on the version that is cheaper for users, more sustainable for relayers, and easier to evolve safely.
Migration to V2
Most bridge traffic has already moved to Snowbridge V2.
Any chain that supports XCM v5 can switch to V2. The Snowbridge team is open to assisting any parachain or application team that needs help with migration.
We encourage remaining V1 users and integrations to begin migration as soon as possible. V2 covers the same core bridging use cases for Asset Hub and XCM v5 parachains, while also enabling newer capabilities such as contract calls and richer cross-chain applications.
Proposed Deprecation Plan
Phase 1: After 7 Days, Relay V1 Only When Profitable
After 7 days, V1 relayers will only relay messages when doing so is profitable.
This will be done off-chain through relayer configuration. The expected result is increased latency for V1 messages, which should discourage new usage and encourage remaining users to migrate to V2.
Phase 2: Rebalance Fee-Paying Sovereign Accounts From Treasury
We propose to rebalance the accounts used to pay V1 relayer rewards:
- Transfer
1000 DOTfrom Treasury to the Asset Hub sovereign account on Bridge Hub. - Swap
500 DOTfor ETH and send it to the Snowbridge Gateway contract.
Note: Snowbridge V1 generated 14,100 DOT in fee revenue to the Polkadot Treasury in the last year. And an extra fees other than relayer rewards go back into the Polkadot Treasury.
This phase is required before increasing V1 fees. The original V1 design depends on balanced fee-paying accounts across the bridge, and these accounts need to be topped up in order to support the increased relayer rewards. Fees are collected into the Snowbridge Gateway contract on Ethereum and the Treasury account on Asset Hub. Rewards are paid from the Snowbridge Gateway contract and the Asset Hub sovereign account on Bridge Hub.
Phase 3: After 30 Days, Increase V1 Fees
After 30 days, V1 fees will be increased to discourage continued usage and to make remaining V1 relaying more sustainable.
Proposed changes:
- Set the on-chain exchange rate to market value:
1 ETH : 1750 DOT. - Set the on-chain gas price to
10 Gwei. - Set relayer rewards to
2 DOTlocally and0.001 ETHremotely.
With these parameters, the Asset Hub base fee would be 9.3364514026 DOT.
The proposed pricing parameters are:
- Exchange rate:
0.0005714285714285715 ETH/DOT, equivalent to1 ETH : 1750 DOT. - Fee per gas:
10 Gwei. - Local reward:
2 DOT. - Remote reward:
0.001 ETH.
For historical context, the original V1 price was approximately 11.45 DOT for Asset Hub to Ethereum transfers. Referendum #1127 later updated Snowbridge pricing parameters to lower transfer fees by reflecting market conditions more closely, reducing the fee to approximately 6.12 DOT. Referendum #1400 then lowered bridge transfer fees further from approximately 6.12 DOT to approximately 1.49 DOT and registered Ether on Asset Hub. These price decreases were not related to costs savings, but rather we chose to subsidise messages to onboard more users, knowing that V2 will eventually replace V1 completely.
The reasoning for increasing V1 fees now is that relayers currently take a loss on some V1 transactions, especially Polkadot to Ethereum transactions, because of stale DOT/ETH exchange rates and Ethereum gas price spikes. V2 avoids these issues through dynamic off-chain pricing.
Phase 4: After 90 Days, Close V1 Channels
After 90 days, we propose closing V1 channels:
- Disable V1 message queues on-chain.
- Remove V1 contract methods on Ethereum.
At this point, remaining users and integrations should have migrated to V2.
Notes on Accounts and Rewards
The V1 design uses governance-controlled accounts for fee collection and reward payment:
- Fees are collected into the Snowbridge Gateway contract on Ethereum and the Treasury account on Asset Hub.
- Rewards are paid out to relayers from the Snowbridge Gateway contract and the Asset Hub sovereign account on Bridge Hub.
- These accounts are permissionless accounts controlled by governance.
- The original V1 design requires these accounts to remain balanced.
Because of this, there will be a separate proposal to top up the Asset Hub sovereign account on Bridge Hub from Treasury.
Call to Action
We encourage all remaining Snowbridge V1 users, parachains, wallets, frontends, and applications to migrate to Snowbridge V2.
Teams that need help migrating to V2 should reach out to the Snowbridge team. Any chain that supports XCM v5 can switch to V2, and we are available to help teams complete the migration.