Mismatching versions of `parity-scale-codec` were found!

Question

Problem

When executing the following command, an error occurred.

cargo contract build
ERROR: Mismatching versions of `parity-scale-codec` were found!
Please ensure that your contract and your ink! dependencies use a compatible version of this package.

Environment

• OS: Ubuntu 20.04 wsl
• cargo-contract: 2.0.0-alpha.3-unknown-x86_64-unknown-linux-gnu
• ink:

  ink = { version = "4.0.0-alpha.3", default-features = false }
  scale = { package = "parity-scale-codec", version = "3", default-features = false, features = ["derive"] }
  scale-info = { version = "2", default-features = false, features = ["derive"], optional = true }
  

• rustc: 1.66.0-nightly

Code

The template code

cargo contract new alpha403

I have checked the version of parity-scale-codec, it is version 3 in both my ink! project and in the ink package of version 4.0.0-alpha.3.

Answer 1

Your problem is that you're using a nightly compiler to build your contract. With the recent alphas it is now possible to build contracts using the stable toolchain.

If you run cargo +stable contract build everything should work as expected.

Answer 2

check out cargo tree, than just:

$ cargo tree | grep scale-codec

To find out if you have multiple dependencies with different versions in the repo