I am building an approval contract in Remix and have been stuck on this issue.

When I try to transfer wei using address.transfer(value), it throws an error. I have marked it in the code below.

Maybe the error is related to the struct Request declared in the constructor because remix debugger ends there when .transfer() fails, I couldn't find an explaination though.

pragma solidity ^0.4.17;

 contract Campaign {
     struct Request {
         string description;
         uint32 value;
         address recipient;
         bool complete;
         uint approvalCount;
         mapping(address => bool) approvals;

     Request[] public requests;
     address public manager;
     uint32 public minimumContribution;
    //  tutorial uses 'approvers' not 'contributors'
     mapping(address => bool) public contributors;
     uint32 public contributorCount;

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

     constructor(uint32 minimum) public {
         manager = msg.sender;
         minimumContribution = minimum;

     function contribute() public payable{
         require(msg.value > minimumContribution);

         contributors[msg.sender] = true; // because contributor is 

     function createRequest(string description, uint32 value, address recipient) 
        public restricted {
         Request memory newRequest = Request({
            description: description, 
            value: value, 
            recipient: recipient, 
            complete: false,
            approvalCount: 0


     function approveRequest(uint16 index) public {
         Request storage r = requests[index];

         // make sure the address has contributed, but has not approved this one yet

         r.approvals[msg.sender] = true;

     function finalizeRequest(uint16 index) public restricted {
         Request storage r = requests[index];

         // make sure more than 50% of contributors approved this request
         require(r.approvalCount > (contributorCount / 2));
         //make sure that this request has not been completed before

         // FAILS ON THIS LINE. Remix debugger goes through this line then ends on line 3 of the contract, in the constructor function. 

         // mark this request as completed
         r.complete = true;


Note the after failing on .transfer(), the debugger jumps up to the constructor function, where struct Request {...} is created. (is this where the problem lies?)

I thought it could be the function .transfer() was being called in, so I attempted to isolate the transfer by calling it in a separate function, but it stilled failed the same way.

Not sure if it helps but the address I input ( the address inaddress.transfer() ) is copied from one of the spare addresses that remix creates in javascriptVM.

  • 1
    If you comment out the line r.recipient.transfer(r.value), does the function succeed? If so, my guess would be that r.value is greater than the contract's balance.
    – user19510
    Jun 2 '18 at 5:16
  • 1
    Perhaps try r.recipient.transfer(address(this).balance); to confirm.
    – user19510
    Jun 2 '18 at 5:17
  • You are right @smarx. It passes when using address(this).balance. Jun 3 '18 at 6:47
  • I will add another require(); ensuring that that r.value is less than the contract balance. Jun 3 '18 at 6:49

The amount of wei specified by r.value was more than is held in the contract. I added a line to my contract to make sure contract contains enough money:

require(address(this).balance > r.value);

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