Here's how you can use this release:

cargo install --force --locked --version 6.0.0-beta.1 cargo-contract 

Compatibility:

• Rust >= 1.88
• ink! 6.0.0-beta.1
• ink-node v0.47.0
• polkadot-sdk from polkadot-sdk/cbab8ed4be1941420dd25dc81102fb79d8e2a7f0 (Oct 15, 2025)
• Paseo Passet Hub (was upgraded here)

Full Changelog

Fixed

• Event decoding when interacting with a contract - 2162
• Accept plain string call arguments by inferring types from metadata - 2161.
• Only use --all-features in cargo contract test when no feature specified - 2164

Version 6.0.0-beta

Here's how you can use this release:

cargo install --force --locked --version 6.0.0-beta cargo-contract 

Compatibility:

• Rust >= 1.88
• ink! 6.0.0-beta
• ink-node v0.46.0
• polkadot-sdk from polkadot-sdk/cbab8ed4be1941420dd25dc81102fb79d8e2a7f0 (Oct 15, 2025)
• Paseo Passet Hub (was upgraded here)

Full Changelog

Added

• Heuristic to distinguish ink! vs. Solidity contracts on-chain ‒ 2147
• Added more output to cargo contract info ‒ 2148

Changed

• Re-enable clippy::cast_possible_truncation lint ‒ #2138
• Synchronize with polkadot-sdk/1b1cef306d9ceebf963fd15a04b5c79ee2618bce ‒ 2675
• Synchronize with polkadot-sdk/cbab8ed4be1941420dd25dc81102fb79d8e2a7f0 ‒ 2153

Fixed

• Support instantiate --code-hash ‒ 2136
• Properly decode Address values inside Vectors ‒ 2137

Version 6.0.0-alpha.4

Compatibility of this release:

• Rust >= 1.88
• ink! v6.0.0-alpha.4
• ink-node v0.45.1
• polkadot-sdk from use-ink/polkadot-sdk/a71ec19a94702ea71767ba5ac97603ea6c6305c1

We have to use a slight fork of polkadot-sdk for the moment. It's just polkadot-sdk/master plus two
commits on top with pre-compiles. Those two commits are PRs to polkadot-sdk. but haven't been merged yet.

To install:

cargo install --force --git https://github.com/use-ink/cargo-contract --tag v6.0.0-alpha.4

Changed

• Handle Rust >= 1.91 change of target-pointer-width JSON type ‒ 2131
• Retrieve the contract address from the Instantiated event ‒ 2134

Version 6.0.0-alpha.3

Compatibility of this release:

• Rust >= 1.88
• ink! v6.0.0-alpha.3
• ink-node v0.45.1
• polkadot-sdk from use-ink/polkadot-sdk/a71ec19a94702ea71767ba5ac97603ea6c6305c1

We have to use a slight fork of polkadot-sdk for the moment. It's just polkadot-sdk/master plus two
commits on top with pre-compiles. Those two commits are PRs to polkadot-sdk. but haven't been merged yet.

To install:

cargo install --force --git https://github.com/use-ink/cargo-contract --tag v6.0.0-alpha.3

Changed

• Upgrade to subxt 0.44 ‒ 2127
• Synchronized with polkadot-sdk/c40b36c3a7c208f9a6837b80812473af3d9ba7f7 ‒ 2102
• Re-enable rustc overflow checks - #2116
• chore: Upgrade to Rust edition 2024 - #2125

Removed

• Removed chain extension functionality ‒ 2120
• Remove MAX_EVENT_TOPICS from Environment implementations - #2122

Intermediate alpha release for cargo-contract.

This release is compatible with:

• polkadot-sdk commit cb629d46ebf00aa65624013a61f9c69ebf02b0b4
• ink! v6.0.0-alpha.1
• ink-node v0.44.0 (notice there are binary releases linked)
• Passet Hub if no newer pull request has been merged than this one

To install this version of cargo-contract:

cargo install --force --git https://github.com/use-ink/cargo-contract --tag v6.0.0-alpha.1

To depend on it:

contract-build = { git = "https://github.com/use-ink/cargo-contract", tag = "v6.0.0-alpha.1" }

This is our first alpha release for cargo-contract v6. We release it together
with ink! v6.0.0-alpha.

The biggest change is that we are in the process of migrating from pallet-contracts +
WebAssembly (executed in wasmi) to pallet-revive +
RISC-V (executed in PolkaVM).
This is a major breaking change, cargo-contract will only be compatible with ink! >= v6
and chains that include pallet-revive.
We did a detailed write-up of the background to this development and the reasoning
here.

Compatibility of this release:

• ink! v6.0.0-alpha
• substrate-contracts-node/9c020a2
• polkadot-sdk/f8c90b2a01ec77579bccd21ae17bd6ff2eeffd6a

In the following we'll describe some breaking changes on a high-level. The
context to understand them is that the pallet-revive team has Ethereum/Solidity
support as the number one priority. All their design decisions derive from that,
they don't want to maintain code that is unnecessary for that objective.

Updated structs + function arguments

We had to change a number of structs and function arguments. Some notable ones:

SourceWasm -> SourceContractBytecode
dest_wasm -> dest_polkavm
optimization_result -> linker_size_result

And v5 ExecuteArgs →
v6.0.0-alpha ExecuteArgs.

We won't describe the other ones here. The best course is to see if you encounter
compilation errors upon upgrading to 6.0.0-alpha. If so, please check our Rust
docs or the cargo-contract source code for how the new format looks and what
the comments say.

The commit that applied the majority of naming changes was
this one.

Types

Contract Balance: U256

For the type of a contract's balance, pallet-revive uses depending on the context

• either the configured pallet_revive::Config::Currency type (which corresponds
  to the ink::Environment::Balance type.
• or a hardcoded U256 (which corresponds to what Ethereum uses).
  In this alpha release we just adhere to requiring the types that pallet-revive uses.
  In an upcoming beta release this could be simplified to reduce UX friction by just
  using one type everywhere and converting to the pallet-revive one.

Contract Address: H160

For a contract's account, pallet-revive is using either the configured AccountId type
of the polkadot-sdk runtime, or H160.

Finding the H160 for an AccountId is done via an address derivation scheme derived in
#7662.
After instantiating a contract, the address is no longer returned by pallet-revive.
Instead one has to derive it from given parameters (see the linked PR). cargo-contract
does that automatically.

For contract instantiations and contract calls the pallet requires that a 1-to-1 mapping
of an AccountId to a H160 has been created. This can be done via the map_account/
unmap_account API.
The PR #6096 contains more
information.

Besides the publicly exposed crate functions, we've introduced a new subcommand
cargo contract account that allows resolving the H160 contract address to the
Substrate AccountId which it is mapped to.

Contract Hash: H256

For a contract's hash value, pallet-revive uses a fixed H256, Previously,
the ink::Environment::Hash type referenced the hash type being used for the
contract's hash. Now it's just a fixed H160.

Events

In #7164, Parity removed
most smart-contract-specific events: Called, ContractCodeUpdated, CodeStored,
CodeRemoved, Terminated, Instantiated, DelegateCalled,
StorageDepositTransferredAndHeld, StorageDepositTransferredAndReleased.

The ContractEmitted event (for events a contract emits) is still available.

Debugging

Previously, pallet-contracts returned a debug_message field with contract
instantiations and dry-runs.
Whenever ink::env::debug_println was invoked in a contract, ink! wrote debugging
info to this field. This functionality has been removed. Instead pallet-revive now
supports other means of debugging.

The most relevant for this release is the tracing API. There are a number of PRs
that implemented it, so we won't link a specific one here. A good starting point
to look deeper into it is the tracing.rs.

We have implemented barebones support for this tracing API in the 6.0.0-alpha
versions of ink! + cargo-contract. But it's really barebones and should
certainly be improved before a production release.

Detection of contract language disabled

The heuristic detection of a contract's language in cargo contract info
has been temporarily disabled; it's not yet implemented.

Contract sizes

Contracts compiled with v6.0.0-alpha will have a large file size. This is due to a number
of bugs in PolkaVM that prohibit us from using e.g. LTO. The contract sizes will eventually
get much smaller again, once those bugs are fixed.

Linting

Linting of a contract can be executed by running the lint command:

➜ cargo contract lint --help
Lint a contract

Usage: cargo contract lint [OPTIONS]

Options:
      --manifest-path <MANIFEST_PATH>
          Path to the `Cargo.toml` of the contract to build

      --quiet
          No output printed to stdout

      --verbose
          Use verbose output

      --extra-lints
          Performs extra linting checks during the build process. Basic clippy lints are deemed important and run anyway.

  -h, --help
          Print help (see a summary with '-h')

Or can be executed programmatically:

let crate_metadata = CrateMetadata::collect(manifest_path)?;
let verbosity = TryFrom::<&VerbosityFlags>::try_from(&self.verbosity)?;

contract_build::lint(extra_lint, &crate_metadata, &verbosity);

Please see #2013 for more information.

Ability to generate Solidity metadata for a contract

ink! v6 will have the ability to speak Solidity, you'll be able to integrate
with tools like Metamask and call ink! contracts from Solidity as if they were
a pre-compile.

We added a new subcommand for this:

cargo contract build ---metadata <ink|solidity>

Please see #1930 for more information.

Changed

• Target pallet-revive instead of pallet-contracts - #1851
• Retrieve PolkaVM target spec from linker - #1939

Added

• Add option to generate Solidity compatible metadata (via cargo contract build ---metadata <ink|solidity>) - #1930
• Deny overflowing (and lossy) integer type cast operations - #1895
• Remove linting by default, --skip-linting and --lint flag in cargo contract build and add a new command lint - #2013

Fixed

• Resolved verifiable-build image failures within release-verifiable-image workflow - #2018

Added

• Deny overflowing (and lossy) integer type cast operations - #1895

Fixed

• Use latest ink! release version in new contract template - #1896

Changed

• Made extrinsic call types, upload, and events public - #1873

Changed

• Bumped the ink! dependencies to ink! 5.1.0 - #1837
• Synchronized the sp-* dependencies with the ones used in ink! 5.1.0 - #1837

This release concludes the migration of ink! from Parity to the outside world. It doesn't come with any new features, we just:

• …changed the Parity URLs to ones for our new GitHub organization
  @use-ink.
• …upgraded many dependencies to newer versions, which results in two particular
  breaking changes regarding compatibility:
  • We had to remove support for Substrate metadata that is below
    V14 in #1722. Metadata formats below V14 are quite old and we hope this doesn't affect anyone.
  • cargo-contract v5 works only with Rust >= 1.81.

For the linter in cargo-contract the Rust toolchain version changed. To upgrade:

export TOOLCHAIN_VERSION=nightly-2024-09-05
rustup install $TOOLCHAIN_VERSION
rustup component add rust-src --toolchain $TOOLCHAIN_VERSION
rustup run $TOOLCHAIN_VERSION cargo install cargo-dylint dylint-link

Changed

• Updated the toolchain version used by ink_linting - #1616
• Update repository URLs & references from paritytech GitHub organization to new use-ink one ‒ #1663
• Bump the version of subxt and subxt-signer - #1722

Removed

• Remove support for V11 metadata #1722