Fusaka is the Berachain upgrade that activates the Fulu + Osaka EL/CL changes shipped to Ethereum in December 2025.Documentation Index
Fetch the complete documentation index at: https://berachain-422fce37-feat-fusaka.mintlify.app/llms.txt
Use this file to discover all available pages before exploring further.
Upgrade timing
| Network | Activation Date (UTC) | Binaries Available |
|---|---|---|
| Bepolia Testnet | 4pm May 27, 2026 | May 11 |
| Mainnet | 4pm June 24, 2026 | June 8 |
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.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.
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.Where to go next
- Running a validator: Validator lifecycle and the validator guides.
- Building on Berachain: Protocol Features.