Stellar Takes Protocol 28 Closer To Mainnet With Testnet Launch

Stellar has moved its Adapter upgrade, Protocol 28, one step closer to a full network rollout after the testnet vote passed on August 27. The mainnet upgrade vote is scheduled for September 16, 2026, at 17:00 UTC.

A Developer-First Upgrade

Unlike some past upgrades that focused mainly on infrastructure, Adapter Protocol 28 is built with developers in mind. Two of its three core changes are aimed directly at making life easier for people building smart contracts on Soroban, Stellar's smart contract platform, while the third strengthens how the network itself reaches consensus.

CAP-83 improves consensus resilience under heavy load, CAP-85 allows atomic upgrades for fleets of Soroban smart contracts, and CAP-86 simplifies contract-data migrations. On the consensus side, consensus keeps moving even when transaction data is slow to propagate, which will improve throughput and help keep the network running smoothly at scale and at low cost. The full performance gains will be phased in after mainnet as parallel transaction-set downloading is gradually enabled.

The release also updates the JavaScript and TypeScript SDKs used to interact with the network. The new SDK simplifies smart contract interactions and improves wallet approval visibility. Its rebuilt XDR layer is now fully typed and replaces Node's Buffer with Uint8Array, reducing a common source of type errors for web developers.

What Builders and Validators Need to Do

Stellar SDK users must upgrade before August 27, 2026, for testnet integration, and before September 16, 2026, for mainnet. Protocol 28 also requires all validators to have synced clocks; validator operators must run NTP sync starting in Protocol 28.

The mainnet vote is scheduled for September 16 at 17:00 UTC. Activation depends on validator approval, so the date represents a planned governance milestone rather than a guaranteed launch. Teams building on the network are being encouraged to start preparing early rather than waiting until the last week, and to keep an eye on Stellar's Developer Discord, where the community is actively coordinating the upgrade.

Sources:
Stellar Development Foundation: Introducing Adapter, Protocol 28
Stellar Development Foundation: Adapter Protocol 28 Upgrade Guide