Can not interact with the deployed contract

Question

getting this error

Error: Transaction reverted: function returned an unexpected amount of data
at Proxy.getDecimals (contracts/proxy.sol:100)
at processTicksAndRejections (node:internal/process/task_queues:95:5)

when using hardhat (forked mainnet/testnet). I am trying to read from a basic function decimals() of WETH.

My implementation is like this

interface ERC20 {
      function decimals() external returns (uint8); 
}

contract Proxy {
      function getDecimals(address _addr) external returns (uint8){
              return ERC20(_addr).decimals();
      }
}

Answer 1

It is due to the decimals() being a non-view function, it should be marked as view function. Try updating your ERC20 interface like this:

interface ERC20 {
    function decimals() external view returns (uint8);
}

Same for getDecimals function.

Also, ensure that the contract you call implements decimals() function, if not you may encounter this error as well.