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Notices are time-bound action items for application developers, node operators, and chain operators: upcoming network upgrades, deprecations, and operational changes. Each hardfork also has a permanent entry in the hardfork registry recording its activation times, governing spec, and minimum component versions, and contract-only upgrades are listed in the registry’s contract upgrades table — notices are archived after activation, registry pages are forever.

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Network upgrades

Upgrade 21

L1 contract upgrade: ETHLockbox as the custody and pause identifier, and the interop contract changes

Interop Activation Prep

OP Mainnet and Unichain interop activation preparation

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Operations

Specialized Node Topology

Guidance for Supernode and Light CL node topology

Subblocks: 200 ms interval and payload changes

A 200 ms subblock interval and four zeroed stream payload fields on OP Sepolia and OP Mainnet

op-reth storage v1 deprecation

op-reth storage v1 reaches end of support on January 26, 2027; migrate existing datadirs to storage v2

Preconfirmation Architecture Transition

OP Labs is ending support for the Flashblocks stack; Subblocks is the supported path