Optimism outlined the timeline for the SuperChain Upgrade 16A, a safety-focused upgrade designed to make the chain more flexible and provide developers with better tools.
summary
- Optimism has announced that the SuperChain Upgrade 16A TestNet will be released on September 22nd and MainNet will be released on October 2nd.
- The upgrade removes unused international withdrawal probing codes and adds system-level functionality for safer and more flexible development.
- OP Contract Manager updates recruitment rationalization without affecting users.
Optimism has announced plans for the next major network upgrade: It aims to increase the safety and flexibility of the entire ecosystem. The upgrade is described as a maintenance release that improves developer tools and prepares the basis for future features.
In an announcement shared via X on September 19th, the team said the upgrade will be revealed at the Super Chain Sepoli Atestnet on September 22nd, reaching the Super Chain Mainnet on October 2nd.
Optimism focuses on safety and flexibility
Upgrade 16A replaces the previous upgrade 16 that contained logic to create drawers that were not activated in the mainnet. Optimism (OP) removes that code from the production path in response to partner feedback and leaves it in the repository for use when interactivity features are prepared for deployment.
With approval of pending governance, Super Chain Upgrade 16A will be proposed for immediate implementation.
📍September 22nd → Super Chain Sepolia
📍October 2nd → Super Chain Main NetThis is a maintenance upgrade that replaces the U16 with a safer and more flexible approach.
What’s changing (and what’s going on…pic.twitter.com/vkm5e0ad5b
– Optimism (@optimism) September 19, 2025
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System-level functionality toggling is an important addition that allows new functionality to be turned on or off per chain without affecting other network nodes. Ethrockbox is the first feature to comply with this mechanism, with potential future applications that include custom gas tokens.
Upgrade 16A also includes feature flags for developers to safely test interoperability in non-production environments, ensuring that the live chain is not affected by experimental code.
A smooth upgrade path for the chain
To streamline recruitment, optimism has updated its OP contract manager. Currently upgraded chains can now be moved directly to 16A, but already upgraded chains can be moved seamlessly without interruption. Importantly, the revisions do not affect end-user behavior or evidence of withdrawal, and highlight optimism’s systematic growth approach.
The upgrade is as optimism continues to drive the superchain framework to position itself as a key hub for Ethereum (ETH) growth. Its reach has increased through partnerships with projects such as Base, Ronin and Unicane, but recent collaborations with concise labs and Flashbots show that they focus on fault prevention, flexibility sequencing, and zero-knowledge technology.
At the time of writing, the OP was trading at $0.835, up 1.2% per day, and 6% last week, with a market capitalization of around $1.49 billion.
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