**Urgent** [Ethereum] - upgrade Sepolia to Fusaka-compatible client releases

Scheduled Maintenance Report for Blockdaemon

Completed

The scheduled maintenance has been completed.
Posted Oct 13, 2025 - 16:00 UTC

In progress

Scheduled maintenance is currently in progress. We will provide updates as necessary.
Posted Oct 13, 2025 - 10:01 UTC

Scheduled

Blockdaemon will update Sepolia Ethereum nodes to Fusaka-compatible client releases on Monday, October 13, 2025.
We are updating our nodes due to the official testnet scheduling for the Osaka/Fusaka fork. There will be planned downtime of up to 15 minutes.

Summary of Technical Changes
• Enables Osaka/Fusaka testnet fork parameters; Sepolia activation is scheduled by clients for October 14, 2025 at 07:36:00 UTC. 
• Geth v1.16.4: activates Osaka on testnets, introduces BPO1/BPO2 blob-capacity fork scheduling for Sepolia, and multiple RPC/core improvements (e.g., engine API BPO support, EVM optimizations, KZG library update). 
• Besu 25.9.0: required for Sepolia ahead of Fusaka; includes breaking/CLI deprecation cleanups, plugin API additions, and performance improvements. 
• Reth v1.8.2: Fusaka-related fixes (e.g., engine getBlobsV1 checks, eth_config), plus stability updates. 
• Consensus clients: Teku 25.9.3 and Nimbus v25.9.2 include testnet scheduling (Sepolia epoch 272640) and high-urgency guidance for impending Fusaka forks; Prysm v6.1.2 ships stability and attestation improvements. 

Customer Impact
During the upgrade window, Sepolia RPC and WebSocket endpoints may intermittently return errors or time out while nodes restart and apply the new configuration. Any interruption should be brief and within the planned 15-minute window. No impact is expected to Ethereum Mainnet or to other networks.

Additional Information
Blockdaemon has validated these client versions for Sepolia and does not anticipate unexpected disruptions beyond the stated downtime.
Release notes:
https://github.com/ethereum/go-ethereum/releases/tag/v1.16.4
https://github.com/hyperledger/besu/releases/tag/25.9.0
https://github.com/paradigmxyz/reth/releases/tag/v1.8.2
https://github.com/NethermindEth/nethermind/releases/tag/1.34.1
https://github.com/OffchainLabs/prysm/releases/tag/v6.1.2
https://github.com/status-im/nimbus-eth2/releases/tag/v25.9.2
https://github.com/Consensys/teku/releases/tag/25.9.3
If you have any questions or concerns, please reach out to your Customer Success Manager.
Posted Oct 13, 2025 - 00:47 UTC
This scheduled maintenance affected: Blockdaemon RPC API (Ethereum Native API) and Protocols (Dedicated Nodes) (Ethereum).