While building the Substrate Kitties Chain using the tutorial: https://docs.substrate.io/tutorials/v3/kitties/pt1/

I got the error like : PS C:\Users\msi\kitties-tutorial> cargo build --release warning: C:\Users\msi\kitties-tutorial\pallets\kitties\Cargo.toml: unused manifest key: dependencies.serde.feature warning: Git command failed with status: exit code: 128 warning: Could not find .git/HEAD searching from C:\Users\msi\kitties-tutorial\node upwards! Compiling node-kitties-runtime v4.0.0-dev (C:\Users\msi\kitties-tutorial\runtime) Compiling pallet-kitties v4.0.0-dev (C:\Users\msi\kitties-tutorial\pallets\kitties) error[E0433]: failed to resolve: use of undeclared crate or module sp_io
--> pallets\kitties\src\lib.rs:4:5 | 4 | use sp_io::hashing::blake2_128; | ^^^^^ use of undeclared crate or module sp_io

error[E0425]: cannot find value blake2_128 in this scope
--> pallets\kitties\src\lib.rs:135:26 | 135 | payload.using_encoded(blake2_128) | ^^^^^^^^^^ help: a unit struct with a similar name exists: Blake2_128 | ::: C:\Users\msi.cargo\git\checkouts\substrate-7e08433d4c370a21\22d40c7\frame\support\src\hash.rs:143:1 | 143 | pub struct Blake2_128; | ---------------------- similarly named unit struct Blake2_128 defined here

warning: unused import: scale_info::TypeInfo --> pallets\kitties\src\lib.rs:2:5 | 2 | use scale_info::TypeInfo; | ^^^^^^^^^^^^^^^^^^^^ | = note: #[warn(unused_imports)] on by default

I have added sp-io crates in pallets\kitties\cargo.toml in [dev-dependincies] as

sp-io = { default-features = false, version = "5.0.0", git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.17" }

and in ["std"] as std = [ "codec/std", "scale-info/std", "frame-support/std", "frame-system/std", "frame-benchmarking/std", "sp-io/std", ]

2 Answers 2


I think you have declare sp-io in [dev-dependencies] if this is true then please moved sp-io from [dev-dependencies] to [dependencies].

  • 1
    This is probably the correct answer.
    – Shawn Tabrizi
    Mar 13, 2022 at 22:00

It seems sp-io is using the v5, whereas the other crates are using v4. try using the v4 of sp-io :

sp-io = { default-features = false, git = 'https://github.com/paritytech/substrate.git', tag = 'devhub/latest', version = '4.0.0-dev' }
  • It starts to give a cargo error: Execution failed (exit code 101). C:/Users/msi/.cargo/bin/cargo.exe metadata --verbose --format-version 1 --all-features stdout : Updating git repository https://github.com/paritytech/substrate.git error: failed to select a version for the requirement sp-io = "^4.0.0-dev" candidate versions found which didn't match: 5.0.0 location searched: Git repository github.com/paritytech/substrate.git?tag=devhub/latest required by package pallet-kitties v4.0.0-dev (C:\Users\msi\kitties-tutorial\pallets\kitties) stderr :
    – Ajit
    Mar 13, 2022 at 12:55

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