Upgrades and migrations

Learn about recent upgrades, breaking changes, and migrations in the ZKsync ecosystem here. For more details, you can check out the ZKsync governance proposals, the CHANGELOG.md and releases for the zksync-era repository.

2025

November 2025

ZK Token Permissionless Burning

• Introduced permissionless burning of the ZK token for any holder.
• Added a BURNER_ROLE to allow certain addresses to burn tokens from designated accounts.
• Added a public max supply of 21 billion ZK, enforced by the token contract.
• Read more details in the official governance proposal.

October 2025

Atlas Upgrade

Introduces ZKsync OS with Airbender as the new system for the ZK Stack, which enables:

• 15K+ TPS with the ZKsync OS sequencer
• 1-second ZK finality via Airbender
• $0.0001 proving cost per transfer

A ZKsync OS CTM was added to support the Atlas upgrade. More details are available in the official governance proposal.

Interop Messaging Upgrade

• Introduced version 29.
• Enabled interop messages between ZKsync chains that settle via ZKsync Gateway.
• Allows block times to be reduced to 200ms.
• New EVM Interpreter pre deployed contracts: Universal deployer and legacy Safe deployers (v1.0.0 to v1.4.1).
• Read more details in the official governance proposal.

June 2025

Precompiles Upgrade

• Introduced version 28.
• Added more efficient versions of ecMul, ecAdd and ecParing precompiles.
• New modexp precompile.
• Read more details in the official governance proposal.

Gateway

• Enabled ZKsync Gateway as an optional aggregation layer for ZKsync Chains.
• Read more details in the official governance proposal.

April 2025

EVM Interpreter Upgrade

• Introduced version 27.
• Added support for EVM contracts, enabling standard EVM tooling for ZKsync.
• Read more details in the official governance proposal.

March 2025

Chain Creation Parameters Upgrade

• Updated chain creation parameters to ensure consistency for genesis batch data.
• Fixed default wrapped base token metadata for genesis upgrades.
• Read more details in the official governance proposal.

February 2025

Preparations for ZKsync Gateway

• Introduced version 26.
• Completed changes necessary to prepare for ZKsync Gateway.
• Added support for custom DA layers.
• Updated the bridging architecture.
• Read more details in the official governance proposal.

Governance Contracts Upgrade

• Reduced the ZIP voting delay from 7 days to 3 days.
• Reduced the quorum extension from 7 days to 2 days.
• Redeployed the ProtocolUpgradeHandler contract to an upgradable version.
• Read more details in the official governance proposal.

2024

December 2024

Reduce Execution Delay

• Reduced the execution delay from 21 hours to 3 hours.
• Read more details in the official governance proposal.

Protocol Defense Upgrade

• Introduced version 25.
• Implemented several code quality improvements and gas optimizations.
• Read more details in the official governance proposal.

September 2024

Governance Rights Upgrade

• Patched version 24.2.
• Transferred the authority for upgrades to ZKsync Nation onchain governance. Read more about how governance works in the ZKsync Nation blog post.

Shared Bridge Upgrade

• Patched version 24.2.
• Introduced a minor change to the BridgeHub contracts which allows the Admin role to add custom base tokens to the system. Previously only the owner of the contract was able to do this. The upgrade was a required step to distinguish the owner and admin role.

August 2024

Shared Bridge Upgrade

• Patched version 24.2.
• Introduced an admin role in the Shared Bridge contract to advance toward decentralized governance.
• The admin is exclusively responsible for nominating L2 bridge counterparts for newly deployed chains.

Elastic Chain Upgrade

• Patched version 24.2.
• Introduced the new ChainAdmin contract interface, which has admin rights over:
  • ZKsync Era Diamond Proxy
  • BridgeHub
  • State Transition Manager
• ChainAdmin acts as a “sovereign” wrapper, allowing each ZKsync Chain to customize configurations like fee parameters and upgrade processes.
• The State Transition Manager (STM) contract now emits events with more detailed upgrade data accessible to other ZKsync Chains.