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Version: 6.x

Migrating from ink! 5.x to 6.0

We've made a couple of breaking changes from ink! 5.x to ink! 6.0. On this page we outline how you can migrate existing dApps and contracts.

You can find the full changelog of the 6.0 release here.

caution

This migration guide only considers your code base! Not your storage data!

If you have an existing contract on-chain you might not be able to just upgrade the code on-chain, you possibly also have to migrate your storage data.

How to upgrade​

  • Change the dependency versions of ink and ink_e2e in your contracts Cargo.toml to 6.
  • Update your local cargo-contract installation to 6.0.
  • Read through this page.

Compatibility​

  • >= polkadot-v1.9.0
  • pallet-contracts >= polkadot-v0.9.37
  • substrate-contracts-node >= v0.24.0

How do I find out if a chain is compatible with ink! 5?​

You can query contracts::palletVersion() via the chain state RPCs. It has to be >= 9 for ink! 5.0 to be compatible, if you don't use any of the four functions mentioned above. For the above mentioned four functions please see the respective sections on this page, there we explain how to find out if a chain supports them there.

You can use the polakdot.js app to connect to the chain and check if reviveApi is available under Developer » Runtime calls.

The following chains are in production and support ink! 6.0.

cargo-contract 6.0​

Together with ink! 6.0 we've released cargo-contract 6.0. You have to use cargo-contract >= 6.0 for ink! 6.0 contracts!

You can upgrade via:

cargo install cargo-contract --version ^6

Tooling & Libraries​

  • Stable Rust >= 1.81
  • cargo-contract >= v6.0
  • polkadot-js/api and polkadot-js/api-contract >= 10.12.1
  • use-inkathon: 10.12.1
  • ink!athon >= 0.7.0

Important Changes​

We had to introduce a number of changes that require you to manually upgrade your contract from 5.x to 6.0. The steps to do this are explained in this section.

Restrict which cfg attributes can be used​

This change was done as a recommendation from the ink! 5.x audit. In a nutshell it prevents developers from hiding functionality in a contract, that would not be visible in the metadata (so e.g. on a block explorer). The relevant PR is #2313.

From ink! 6.0 on only these attributes are allowed in #[cfg(…)]:

  • test
  • feature (without std)
  • any
  • not
  • all

Interesting New Features​