Stellar Protocol 18 introduces breaking changes including Automated Market Makers (AMMs) and liquidity pools. Developers and node operators must upgrade Stellar Core, Horizon, and all SDKs before the November 3, 2021 upgrade vote to ensure compatibility.
Protocol 18 enables Automated Market Makers (AMMs) on Stellar by introducing liquidity pools, which represent a significant upgrade to the network. The upgrade introduces breaking changes affecting API responses, asset types, trustlines, and trade price precision. Node operators must upgrade to Stellar Core v18.1.0 and Horizon v2.10.0, while developers must update their SDKs (JavaScript, Java, Go, Python, iOS, C#, Flutter, Ruby) to compatible versions. Key changes include new liquidity pool asset types, modified trustline responses, new balance types for liquidity pools, trade price type changes from int32 to int64 (represented as strings), and XDR format updates. The testnet upgrade occurred October 6, 2021, with the public network upgrade vote scheduled for November 3, 2021 at 1500 UTC. Upgrading sooner rather than later is recommended since new software is compatible with the current protocol.
