Immutable announces that Immutable Chain will upgrade to OP Stack in 2027
Immutable posted on X that Immutable Chain will upgrade in 2027 from a custom geth fork to a chain based on OP Stack. After the upgrade, on-chain transaction speeds will increase, and the chain will establish a closer connection to Ethereum’s security. All accounts, balances and contracts will be migrated automatically, and almost all users will not need to take any action.
Official documentation shows that the mainnet migration target is mid-2027, and the public testnet migration will be completed in the first quarter of 2027 beforehand. Block time is planned to be shortened from 2 seconds to 1 second. Native withdrawal time will be extended to about 7 days, and transaction costs will rise slightly. The current testnet will stop being used for game testing by the end of 2026.
Original source:
Title: OP Stack Migration - Documentation Publisher: Immutable Publication date: November 5, 2026 (document updated) URL: https://docs.immutable.com/docs/products/immutable-chain/op-stack-migration Source nature: Official company technical documentation Verification status: The full document and the corresponding X post were read; the core facts (upgrade from a custom geth fork to OP Stack in 2027, mainnet target of mid-2027, testnet Q1 2027, automatic migration of accounts/balances/contracts, almost no user action required, block time from 2 seconds to 1 second, native withdrawal about 7 days, slightly higher transaction costs, and testnet ending game testing at the end of 2026) all directly correspond to the official statements Supporting content: Explanation of the upgrade architecture, timeline and user impact
ABAB AI Insight
The upgrade will turn Immutable Chain from a custom geth-fork sidechain into an Ethereum rollup based on OP Stack. The state, Chain ID, accounts, balances and contracts remain unchanged.
The shorter block time and the introduction of Ethereum data availability make the chain’s connection to Ethereum’s security model more direct. The native bridge will switch from Axelar to the OP Stack native bridge.
The native withdrawal period will be extended to about 7 days, and transaction costs will increase due to the fees for publishing data to Ethereum. Most users use third-party fast bridges, so the actual impact depends on each person’s path.
During the migration, block production is expected to pause for several hours, and the specific date will be announced in advance once confirmed. Support for testnet game testing will end at the end of 2026, and developers will need to switch to local chains or mainnet.
ABAB News · Cognitive Law
Moving from a custom geth-fork to an OP Stack rollup allows Immutable Chain to connect to Ethereum data availability while preserving state.
The longer native withdrawal period and higher transaction costs constitute clear changes to the user path after the upgrade.