Blog Article

Protocol 20 Upgrade Guide


Justin Rice

Publishing date

Protocol upgrade

This guide is designed to help developers and businesses building on the Stellar network prepare for the network upgrade to Protocol 20, which introduces support for Soroban smart contracts.

It's by far the biggest, most complex protocol upgrade to date, and so while the basic instructions to prepare are the same as ever — install up-to-date versions of any Stellar-related software you use! — the process will take a few extra steps and play out a bit slower than usual.

The Testnet successfully upgraded Wednesday, September 20 at 1500 UTC to release candidate versions of Stellar Core and Horizon. Mainnet validators will likely schedule an upgrade vote date for 6 weeks after stable releases come out, and as soon as that happens, we will update this doc to include it.

Because the Protocol 20 upgrade introduces new network settings that validators control, it is also likely that the initial upgrade vote will be followed by a series of additional votes to adjust those settings, and when there is a timeline for those votes, we will also add them to this doc. In general, we will keep this doc up to date as new information comes in, and as new releases come out.

To stay informed, ask questions, make suggestions, or share intel, make sure to join the Stellar Developer Discord and check out the #protocol-20 channel, which is where the ecosystem is coordinating and sharing information about the upgrade.

What do you need to do to prepare for the Testnet upgrade?

Upgrade to the latest version of the SDK. Even if your application doesn’t involve Soroban-related functionality, this is necessary so that it can decode Soroban-related operations, which it may encounter while ingesting network data. If you happen to run Testnet infrastructure, make sure to install the new versions of Horizon and Stellar Core, and if your Testnet validator is configured to participate in consensus, arm it for the upgrade with the following command:


For Soroban projects, you'll also need to update soroban-sdk to "20.0.0-rc2" in your project's cargo.toml file.

Key dates

New dates will be added as new information comes in.

  • September 20, 1500 UTC — Testnet upgrade
  • TBD — Public network upgrade vote

Protocol 20 releases

We're gathering a list of software that needs updating below. We will continue to add links to Protocol-20-related releases as soon as they come out. For the time being, developers should hold off on using these releases on Mainnet. In general, please make sure to check release notes for specific instructions and requirements.

Stellar infrastructure

Those who operate Testnet nodes need to install the latest version of Stellar Core and Horizon.


For developers, links to the relevant release page (with minimum SDK version listed in parenthesis) are here. We will continue to update this list as new releases come out.


Join the Stellar Developers Discord

The #protocol-20 channel is now live, so join the conversation!