# OP Stack Predeploy Upgrades *The L2ContractManager enables OP Stack chains to automatically upgrade predeploy contracts at the hardfork block.* By [ETH Daily](https://ethdaily.io) ยท 2026-06-27 infrastructure, scaling, optimism, layer-2 --- OP Labs [introduced](https://optimism.io/blog/unlocking-predeploy-upgrades-for-the-op-stack-with-nuts) a new framework called the L2ContractManager, enabling OP Stack chains to automatically upgrade their Layer 2 predeploy contracts during hardforks without needing manual multisig transactions. Predeploys are Solidity smart contracts included in the L2 genesis state, such as L1Block and 26 other active proxies, that have historically been difficult to upgrade due to the operational complexity of coordinating multisig signs across numerous network instances. The new system, landing in the upcoming Karst upgrade, utilizes Network Upgrade Transactions (NUTs) injected directly at the hardfork activation block. A script in the Optimism monorepo generates a json bundle defining the set of upgrade interactions, which in the Karst upgrade translates to 31 distinct transactions. These transactions deploy a ConditionalDeployer contract, spin up new implementation bytecodes, upgrade the L2ProxyAdmin to support batch upgrades, and deploy the one-time L2ContractsManager contract to execute the final upgrades via delegatecall. This setup ensures all 27 maintained predeploys are updated and configured in the very first block of the hardfork while keeping consensus clients like op-node and kona in perfect sync. * * * Disclaimer: Content is for informational and educational purposes only and does not constitute financial, investment, legal, or other professional advice. No representations or warranties are made as to accuracy, completeness, or timeliness. Use of this content is at your own risk, and you should consult a qualified professional before making decisions. No fiduciary or advisory relationship is created --- *Originally published on [ETH Daily](https://ethdaily.io/op-stack-predeploy-upgrades-nuts)*