With the updated version of etherscan V1 -> V2 the chainId is missing

[kharchafiabdallah]

When I verify a transparent upgradeable contract and after upgrading to version 2 of Etherscan https://docs.etherscan.io/etherscan-v2, you need to inject the chain id into the query parameters, otherwise you get the following error:

Etherscan returned with message: NOTOK, reason: Missing chainid parameter (required for v2 api), please see https://api.etherscan.io/v2/chainlist for the list of supported chainids

I think modifying line 17 of packages/plugin-hardhat/src/utils/etherscan-api.ts to
const parameters = { ...params, chainid: etherscan.chainId, apikey: etherscan.apiKey };
should fix the problem.

So i don't know if you already have a fix somewhere or we have missed something in the configuration

[ericglau]

Thanks for reporting this issue. Would you be interested in contributing a PR? Here is an example of how we can get the current chainId.