pub fn create_full<C, P>(
    deps: FullDeps<C, P>,
) -> Result<RpcExtension, Box<dyn std::error::Error + Send + Sync>>
    C: ProvideRuntimeApi<Block>
        + HeaderBackend<Block>
        + AuxStore
        + HeaderMetadata<Block, Error = BlockChainError>
        + Send
        + Sync
        + 'static,
    C::Api: pallet_transaction_payment_rpc::TransactionPaymentRuntimeApi<Block, Balance>,
    C::Api: substrate_frame_rpc_system::AccountNonceApi<Block, AccountId, Nonce>,
    C::Api: pallet_contracts_rpc::ContractsRuntimeApi<Block, AccountId, Balance, BlockNumber, Hash>,
    C::Api: BlockBuilder<Block>,
    P: TransactionPool + Sync + Send + 'static,
    use pallet_contracts_rpc::{Contracts, ContractsApiServer};
    use pallet_transaction_payment_rpc::{TransactionPayment, TransactionPaymentApiServer};
    use substrate_frame_rpc_system::{System, SystemApiServer};

    let mut module = RpcExtension::new(());
    let FullDeps { client, pool, deny_unsafe } = deps;

    module.merge(System::new(client.clone(), pool, deny_unsafe).into_rpc())?;


I inserted a constraint to the standard rpc.rs create_full function:

C::Api: pallet_contracts_rpc::ContractsRuntimeApi<Block, AccountId, Balance, BlockNumber, Hash>,

I got an error:

C::Api: pallet_contracts_rpc::ContractsRuntimeApi<Block, AccountId, Balance, BlockNumber, Hash>,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `create_full`
 -> Result<Box<dyn ParachainConsensus<Block>>, sc_service::Error>, <RuntimeApi as ConstructRuntimeApi<sp_runtime::generic::Block<sp_runtime::generic::Header<u32, BlakeTwo256>, OpaqueExtrinsic>, sc_service::client::client::Client<sc_client_db::Backend<sp_runtime::generic::Block<sp_runtime::generic::Header<u32, BlakeTwo256>, OpaqueExtrinsic>>, LocalCallExecutor<sp_runtime::generic::Block<sp_runtime::generic::Header<u32, BlakeTwo256>, OpaqueExtrinsic>, sc_client_db::Backend<sp_runtime::generic::Block<sp_runtime::generic::Header<u32, BlakeTwo256>, OpaqueExtrinsic>>, NativeElseWasmExecutor<Executor>>, sp_runtime::generic::Block<sp_runtime::generic::Header<u32, BlakeTwo256>, OpaqueExtrinsic>, RuntimeApi>>>::RuntimeApi: ContractsRuntimeApi<sp_runtime::generic::Block<sp_runtime::generic::Header<u32, BlakeTwo256>, OpaqueExtrinsic>, sp_runtime::AccountId32, u128, u32, H256>

Any suggestion what should I do is greatly appreciated.

1 Answer 1


It means that C doesn't implement this trait.

Check the C, the create_fuill<C, P>'s C.

After taking a look at your code.

I think you missed the trait bound here https://github.com/hgminerva/humidefi-parachain/blob/015d477ee6a73479760d4ea072ce871e970a0d43/node/src/service.rs#L86-L93.


RuntimeApi::RuntimeApi: ContractApi

Made a PR to your repo https://github.com/hgminerva/humidefi-parachain/pull/1.

  • Sorry for being so novice, any hint will help on how to check C, all seems to match existing code in contract nodes, etc.
    – hgminerva
    Oct 30, 2022 at 11:16
  • Without the full code, I can't do any further diagnosis. Maybe you missed github.com/paritytech/substrate/blob/…. Oct 30, 2022 at 11:19
  • in my runtime i am using this: impl pallet_contracts_rpc_runtime_api::ContractsApi<Block, AccountId, Balance, BlockNumber, Hash>
    – hgminerva
    Oct 30, 2022 at 11:28
  • I posted the code above.
    – hgminerva
    Oct 30, 2022 at 11:33
  • 1
    No, you don't. Check github.com/hgminerva/humidefi-parachain/pull/1. Still recommending you learn some Rust first. I have already given the answer to you and you said you have tried that... Oct 31, 2022 at 3:41

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