transaction failed Error: createType(SignerPayload):: Struct: failed on assetId: Option<AssetId>:: Unable to construct number from multi-key object

Question

Does anyone know how to solve this error?

I am trying to pay transaction fees with sufficient tokens on Westend Asset Hub by passing an asset MultiLocation to the options in the signAndSend function.

const asset = {
  parents: 0,
  interior: {
    X2: [{ palletInstance: 50 }, { generalIndex: 8 }],
  },
};

const injector = await web3FromSource(account.meta.source);

    transferExtrinsic
      .signAndSend(
        account.address,
        {
          signer: injector.signer,
          assetId: asset,
        },
        ({ status }) => {
          if (status.isInBlock) {
            console.log(
              `Completed at block hash #${status.asInBlock.toString()}`
            );
          } else {
            console.log(`Current status: ${status.type}`);
          }
        }
      )
      .catch((error) => {
        console.log(":( transaction failed", error);
      });
  };

And I keep getting this console error regarding the asset MultiLocation format is incorrect when using Talisman Wallet

transaction failed Error: createType(SignerPayload):: Struct: failed on assetId: Option<AssetId>:: Unable to construct number from multi-key object

And here is the error message when using Polkadot.js extension

Something went wrong with the query and rendering of this component. createType(ExtrinsicPayload):: createType(ExtrinsicPayloadV4):: Struct: failed on assetId: Option<AssetId>:: Assertion failed

I am getting the same error when capitalizing PalletInstance and GeneralIndex like this

const asset = {
  parents: 0,
  interior: {
    X2: [{ PalletInstance: 50 }, { GeneralIndex: 8 }],
  },
};

Answer 1

You have to choose the XCM version for your asset MultiLocation

Try with:

const asset = { 
  v4: { 
    parents: 0,
    interior: { 
       x2: [{ PalletInstance: 50 }, { GeneralIndex: 8 }]
     }
  }
};