Stellar is preparing Protocol 28, known as Adapter, for testnet and mainnet votes scheduled August 27 and September 16 respectively, according to the protocol upgrade announcement.
The upgrade bundles three capability proposals aimed at improving network performance and contract operations. CAP-83 is designed to improve consensus performance when transaction data propagates slowly. CAP-85 will allow multiple smart contracts sharing code to be upgraded together in a single atomic operation. CAP-86 introduces new sparse map functions to make contract data migrations easier.
Stellar's testnet vote on August 27 comes first, giving validators and SDK users a window to test the upgrade's behavior before the mainnet vote on September 16. The foundation recommends SDK users update their implementations before each respective deadline to ensure compatibility with the new protocol version.
Protocol upgrades on Stellar require validator consensus before activation. The staggered voting schedule between testnet and mainnet is standard practice, allowing developers to identify and address issues on the test network before the change takes effect on the live network where transactions carry real value.
Adapter builds on Stellar's previous protocol versions, which have added capabilities like custom assets, multi-signature support, and smart contract functionality. The foundation has been incrementally expanding Stellar's developer toolkit over successive protocol releases.
The three improvements address different layers of contract and consensus operation. Atomic contract upgrades simplify fleet management for applications deploying multiple interdependent contracts. Sparse maps reduce storage overhead for contracts that maintain large collections with sparse data patterns. The consensus improvement targets a specific performance scenario where validators must wait for transaction data to arrive before proceeding.
Stellar users and validators can review the full upgrade specifications and begin testing against testnet deployments in the coming weeks. The September 16 mainnet vote will determine whether the protocol changes activate network-wide.
