Sepolia Testnet: Base Cobalt Upgrade - September 23rd

Scheduled for Sep 23, 18:00 - 20:00 UTC

Scheduled

On Wednesday, September 23rd at 18:00 UTC (Unix timestamp 1790186400), the Base Sepolia Testnet will undergo the Cobalt upgrade.

Operators of Base Sepolia Testnet nodes must upgrade to the 1.4.0, or greater, release of the https://github.com/base/base software (https://github.com/base/base/releases/tag/v1.4.0).

Please note: https://github.com/base/base now hosts the public Base node previously published from base/node. More information can be found here: https://github.com/base/base#run-a-node

For more information on the Cobalt upgrade, please visit our docs: https://docs.base.org/upgrades/cobalt/overview.

Posted Sep 16, 2026 - 21:22 UTC

This scheduled maintenance affects: Testnet (Client Software).