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Documentation Index

Fetch the complete documentation index at: https://docs.berachain.com/llms.txt

Use this file to discover all available pages before exploring further.

Fusaka is the Berachain upgrade that activates the Fulu + Osaka EL/CL changes shipped to Ethereum in December 2025.

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Upgrade timing

NetworkActivation Date (UTC)Binaries Available
Bepolia Testnet4pm May 27, 2026May 11
Mainnet4pm June 24, 2026June 8
The official binaries will ship at Github (Bera-Reth, BeaconKit), with announcements posted to Telegram and Discord, along with updates to our recommended versions page.

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Bera-Geth Will Stop Working

With this upgrade, Berachain is completing the Bera-Geth deprecation previously announced. After this fork, Bera-Geth clients will stop following the chain. Follow our migration guide to install Bera-Reth.

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For developers

Bera-Reth in this upgrade bumps the upstream Reth dependency to v1.11.4. EIP-6110: Deposits process in the block they are submitted in. Pre-Fusaka, deposits and withdrawals were processed every epoch (192 blocks). No longer. A deposit transaction emits its event, the execution client parses it into a deposit request, and the consensus client consumes that request — all in the same block. (A validator’s effective balance, which determines voting power and activation status, is still only updated at the turn of an epoch.) Reference: Become a validator. Additional EIPs being activated:
  • EIP-7951 (P-256 precompile): Native verification of passkey and hardware-key signatures, usable for smart-account flows backed by WebAuthn, Apple Secure Enclave, Android Keystore, and HSMs.
  • EIP-7939 (CLZ opcode): A faster bit-math primitive that returns the position of the leading set bit in a single opcode.
  • EIP-7823 & EIP-7883 (MODEXP repricing and bounds): Repriced modular exponentiation, with an input-size bound (capped at 8,192 bits) that rejects oversized arguments outright.
  • Code-size limits (EIP-7954 aligned): Expanded contract code and initcode size limits (32 KB and 64 KB, respectively), raising the ceiling on what a single contract can deploy.
  • EIP-7934 & EIP-7825 (Size caps): Defense-in-depth caps on block size (10 MiB) and per-transaction gas (16.7M gas), sized well above current usage.
Reference: Protocol Features.

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For validators

Effective balance updates respond more closely to actual stake. The hysteresis buffers that govern when a balance change triggers an effective-balance update are tightened. A drop of -100 BERA or +1000 BERA will update the validator’s voting power. Reference: Validator lifecycle, Increase validator stake.

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Upgrade instructions

This release of Bera-Reth introduces a major quality-of-life improvement for node operators: you can now specify the network chain directly with --chain bepolia or --chain mainnet. With this approach, there is no longer any need to manually fetch or deploy updated genesis files when upgrading. Bera-Reth will select the correct built-in configuration based on your chosen network. In addition, when using the new --chain option, you do not need to provide --bootnodes; Bera-Reth will automatically use the appropriate bootnode list for the selected chain. The old style of --chain <path> still works, but you must be sure to fetch and deploy the genesis files linked from our release page.
  1. If you are running Bera-Geth, you have to migrate to Bera-Reth.
  2. DO NOT deploy this on a mainnet node until 1.4.0 (non-rc) binaries designated for mainnet are released.
  3. Download the current releases of BeaconKit and Bera-Reth from the recommended versions page.
  4. Adjust Bera-Reth startup:
    • Change your --chain option to --chain bepolia and remove --bootnodes.
    • OR download and fetch the current bepolia genesis file from the recommended versions page, and overwrite your current genesis file with it.
  5. No changes are needed to BeaconKit options.
  6. Start the new beacond and bera-reth binaries.

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Support

If you have questions about this upgrade, the best place for support is our Discord’s #node-support channel.