Breaking Changes for Relayers

Relayers must update their event subscriptions and fill functions to support the new event formats introduced in the non-EVM migration.

Event Changes

Three events that relayers depend on are being deprecated and replaced:

Key Differences

• Address types: All address fields → bytes32 to support non-EVM chains
• Gas optimization: FilledRelay contains only the messageHash instead of the full message
• Deposit ID: uint32 → uint256

Migration Strategy

Query both old and new event types to ensure a smooth transition. Each SpokePool upgrades at a different time, but the protocol guarantees no single fill or deposit will emit duplicate events.

// Monitor both old and new deposit events
// Old: V3FundsDeposited (address types, uint32 depositId)
// New: FundsDeposited (bytes32 types, uint256 depositId)

// Process whichever event you receive — they won't overlap

New fillRelay Function

The new fillRelay function replaces fillV3Relay and adds:

• Repayment address selection — Relayers can designate a repayment address different from the fill-executing address
• Non-EVM fill capabilities — Supports filling on non-EVM chains