Legacy Bridge Deprecation & Migration to SharedBridge

[uF4No]

When ZKsync Era launched in March 2023, it was built as a single-chain system. At the time, the L1 bridge contract was designed specifically for that environment.

Fast forward to today, and ZKsync has evolved into the Elastic Network—a cluster of many interoperable ZK chains. To support this shift, we introduced a major protocol upgrade in June 2024 (v24).

Protocol v24 brought a new BridgeHub contract on Ethereum mainnet, designed for multiple chains, and a l1SharedDefaultBridge to support bridging across the entire Elastic Network. All official tools—including the ZKsync bridge UI and SDKs—were updated to use the l1SharedDefaultBridge.

As announced in December 2024, usage of the original legacy bridge was discouraged. With the legacy bridge now approaching deprecation, we’re issuing a new reminder.

ℹ️ Learn more about protocol v24 in this announcement.

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🔧 Required Migration for Applications

If your application still uses the legacy bridge (l1Erc20DefaultBridge):

• Mainnet legacy bridge: 0x57891966931Eb4Bb6FB81430E6cE0A03AAbDe063
• Testnet legacy bridge: 0x2ae09702f77a4940621572fbcdae2382d44a2cba

You must migrate to the new l1SharedDefaultBridge contract:

• l1SharedDefaultBridge mainnet: 0x8829ad80e425c646dab305381ff105169feece56
• l1SharedDefaultBridge testnet: 0xf2a49545c5b1a85d2fb018cc39103661639a9b06

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🧪 How to Know If You're Affected

• If your application is retrieving the bridge address using the RPC method zks_getBridgeContracts, switch to use the l1SharedDefaultBridge from the response, instead of l1Erc20DefaultBridge.
• The following versions of the ZKsync SDKs use the legacy bridge in the deposit and withdraw methods:
  • Javascript SDK (zksync-ethers) version 6.7.2 (ethers v6) / 5.7.2 (ethers v5) or below.
  • Go SDK, versions 0.4.0 or below.
  • Python SDK, version 1.1.0 or below
  • Java SDK, version 0.2.1 or below.

All SDK versions released after the mentioned above, use the l1SharedDefaultBridge.

If you're unsure whether your system uses the legacy bridge, we strongly recommend checking with your engineering team or reaching out to us directly.

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📆 What’s Next?

The legacy bridge is planned to be deprecated in June 2025, and once that happens, transactions routed through it may fail or result in unexpected behavior.

To avoid service disruptions for your users:

• ✅ Update your apps to use l1SharedDefaultBridge from the zks_getBridgeContracts reponse.
• ✅ Update the ZKsync SDKs in you apps.
• ✅ Migrate any other smart contracts to use l1SharedDefaultBridge.
• ✅ Double-check that no legacy bridge dependencies remain.

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Need Help?

We’re here to assist with the migration. Feel free to reach out:

• Reply to this post
• DM us on X @zksyncdevs

Let’s make this transition smooth for everyone building on ZKsync 💪