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Osaka1 is a Berachain-specific execution-layer hardfork that floors the minimum base fee and minimum blob base fee at 1 gwei each after activation.

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Upgrade timing

NetworkActivation Date (UTC)Binaries Available
Bepolia Testnet4pm July 22, 2026July 14
MainnetPlaceholder activation time—

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What changes

After the fork activates, Bera-Reth enforces configurable floors on the two EIP-1559 fee parameters:
  • Minimum base fee: 1 gwei (1_000_000_000 wei). The next-block base fee can no longer decay below this value.
  • Minimum blob base fee: 1 gwei (1_000_000_000 wei). The EIP-4844 blob base fee is lifted to this floor, shifting the entire exponential curve baseline.

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Configuration

Osaka1 is carried in the built-in --chain bepolia preset shipped with Bera-Reth v1.4.3-rc.0. The Berachain genesis berachain.osaka1 block for Bepolia is:
1784736000 is 2026-07-22 16:00:00 UTC. The matching chainspec is available in the Beacon Kit v1.4.2-rc.0 genesis file.

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Upgrade instructions

  1. Download the recommended versions for Bepolia:
    • Bera-Reth v1.4.3-rc.0
    • Beacon-Kit v1.4.2-rc.0
  2. If you use the built-in chain preset, keep your Bera-Reth startup as --chain bepolia. The preset carries Osaka1 automatically; no genesis file change is needed.
  3. If you use --chain <path>, fetch the Bepolia genesis from Beacon Kit v1.4.2-rc.0 and overwrite your current genesis file. Verify the md5: f7d31d1039b0253f5f43336e55d28054.
  4. No changes are needed to BeaconKit options.
  5. Start the new beacond and bera-reth binaries.