Hardhat+Etherscan contract verification from deployment failed

[Habeebullahi01]

This is just a tip in case your contract didn't get verified on Etherscan after you included the verify task in your deploy.js file.

Situation

You added the code to verify your contract on etherscan into your deploy.js file (or anywhere). You run the code, and it exits with no error and everything is fine.
You view the contract on etherscan and it's not verified.

Reason

Hardhat compiles the SimpleStorage.sol using the compiler version stated in the hardhat.config.js file. Etherscan seems to compile the contract using the compiler version stated in the SimpleStorage.sol file. In this case, Etherscan will compile it with the latest compiler version (0.8.15 at the time of writing). The compiled bytecode that was created by Hardhat after compilation on your local machine will be compared to the bytecode that is produced by Etherscan after compiling on their own end. If compiler versions are different, resulting bytecodes will also be different.
This maybe because your SimpleStorage.sol does not specify the version of compiler to use, it has a range like pragma solidity ^0.8.8.

Solution

Hardhat and Etherscan have to compile the contract with the same compiler version. There are 2 ways to achieve this:

1. Use a specific compiler version all the way. Be specific in your contract and in your hardhat.config.js as to which compiler version to use.
2. Add the highest extreme of the compiler version in your contract to your hardhat.config.js. You can read more about this here

I hope this helps to solve your problem.

[PatrickAlphaC]

Thanks for this!