How to resolve this error in solidity “The constructor should be payable if you send value.”?

Question

In this solidity code the finalizeRequest() is giving a run-time error. Here is the error :

Campaign.finalizeRequest(uint256) 0x692...77b3a

transact to Campaign.finalizeRequest errored: VM error: revert.
revert  The transaction has been reverted to the initial state.
Note: The constructor should be payable if you send value.  Debug the transaction to get more information.

Here is the code:

pragma solidity ^0.5.14;

contract Campaign {
    struct Request {
        string description;
        uint value;
        address payable recipient;
        bool complete;
        uint approvalCount;
        mapping (address => bool) approvals;
    }

    address public manager;
    uint public minimumContribution;
    // address[] public approvers;
    mapping (address => bool) public approvers;
    Request[] public requests;
    uint public approversCount;


    constructor(uint minimum) public {
        manager=msg.sender;
        minimumContribution=minimum;
    }

    function contribute() public payable {
        require(msg.value>minimumContribution);
        // approvers.push(msg.sender);
        approvers[msg.sender]=true;
        approversCount++;
    }

    function createRequest(string memory description,uint value,address payable recipient) public restricted {
        // require (approvers[msg.sender]);    
        Request memory newRequest=Request({description:description,value:value,recipient:recipient,complete:false,approvalCount:0});
        requests.push(newRequest);

    }

    function approveRequest(uint index) public {
        Request storage request=requests[index];

        require(approvers[msg.sender]);
        require(!request.approvals[msg.sender]);
        request.approvals[msg.sender]=true;
        request.approvalCount++;
    } 

    function finalizeRequest(uint index) public restricted payable{
        Request storage request = requests[index];

        require(request.approvalCount>=(approversCount/2));
        require(!request.complete);
        request.recipient.transfer(request.value);
        request.complete=true;

    } 

    modifier restricted() {
        require (msg.sender == manager);
        _;
    }
}

As far as I could debug, when I comment out request.recipient.transfer(request.value); in the finalizeRequest() function no runtime error is thrown. So error seems to be in this line of code ,kindly help resolving this.

Answer 1

The error message is misleading. You can safely disregard it since you aren't calling the constructor or sending funds.

It's a lot of code to wade through so this won't be very specific.

You say this seems to be the issue:

request.recipient.transfer(request.value);

The most likely cause is the contract doesn't have sufficient funds to make that happen. It cannot transfer ether it doesn't have. So, back up a step and make sure contribute is doing what you think it does. Consider adding:

function contractBalance() public view returns(uint) {
  return address(this).balance;
}

Also watch the request.value. Be sure it isn't more than the contract has. Possibly accounting errors are causing trouble.

You can use a newer compiler (0.4.17 is very old) and add revert reasons:

require(true, "How could that not be true? Something seriously haywire.");

This will not catch the specific transfer error which is protocol error. You might consider commenting out the offending statement, and logging an event again.

Something like:

// request.recipient.transfer(request.value);
emit LogDebug(request.value, address(this).balance);

Hope it helps.