Skip to main content

Contract Verification

Once you have deployed your smart contracts, you can verify them on the explorer. The following guide uses hardhat.

Via Flattened Source Code​

  1. Use the following command to get a flattened source code of your smart contract:
npx hardhat flatten path/to/your/contract.sol
  1. Find your deployed contract on the Kava explorer and follow the steps to verify. If your contract has constructor arguments, ensure that you provide them in the form. If you do not already have an ABI-encoded version of it, you can use this online ABI encoding tool to manually create it. Additional information about ABI-Encoded constructor arguments can be found on the Blockscout documentation.

Via Hardhat Verification Plugin​

You can also verify directly from your Hardhat development environment. This requires the hardhat-etherscan plugin. The Kava explorer uses BlockScout which is compatible with the Hardhat Etherscan plugin.

  1. Install the Hardhat Etherscan plugin, ensuring that the version is v3.1.0 or higher.
  2. Ensure your hardhat.config.js file includes the following etherscan configuration:
hardhat.config.js
module.exports = {
  networks: {
    kava: {
      url: 'https://evm.kava.io',
    },
  },
  etherscan: {
    apiKey: {
      kava: "api key is not required by the Kava explorer, but can't be empty",
    },
    customChains: [
      {
        network: 'kava',
        chainId: 2222,
        urls: {
          apiURL: 'https://kavascan.com/api',
          browserURL: 'https://kavascan.com',
        },
      },
    ],
  },
};
  1. Verify that the custom network is configured correctly, by checking if kava is listed in the supported custom networks.
$ npx hardhat verify --list-networks

Networks supported by hardhat-etherscan:

...

Custom networks added by you or by plugins:

╔═════════╤══════════╗
║ network │ chain id ║
╟─────────┼──────────╢
║ kava    │ 2222     ║
╚═════════╧══════════╝
  1. Verify the contract with npx hardhat verify. This may take a few minutes. The following is an example of verifying an WKAVA contract.
$ npx hardhat verify --network kava 0x52A87b0703C65a4C30657e7badc808855711CdEc

Nothing to compile
Generating typings for: 0 artifacts in dir: typechain-types for target: ethers-v5
Successfully generated 3 typings!
Successfully generated 3 typings for external artifacts!
Compiling 1 file with 0.8.9
Successfully submitted source code for contract
contracts/WKAVA.sol:WKAVA at 0x52A87b0703C65a4C30657e7badc808855711CdEc
for verification on the block explorer. Waiting for verification result...

Successfully verified contract WKAVA on Etherscan.
https://kavascan.com/address/0x52A87b0703C65a4C30657e7badc808855711CdEc#code

Troubleshooting​

Here are some common errors and things to look out for when verifying your contracts.

Bytecode does not match, please try again.​

Ensure the following options are the exact same as what you deployed with, then try again.

  • Compiler version
  • Optimization runs
  • ABI-encoded constructur arguments

There was an error compiling your contract: Multiple SPDX license identifiers found in source file​

Flattening your contracts may sometimes merge multiple dependent contracts also with SPX identifiers (e.g. // SPDX-License-Identifier: GPL-3.0).

Remove all SPDX comments except one in your flattened file and try verifying again. Alternatively, use the hardhat verification plugin to preserve license identifiers.

Resources​