I am beginner in Solidity, So my problem maybe simple. I have two contracts "BankA" and "customer". Whenever i deploy BankA in Truffle network and call pay() the following Error will emerge:

Error: Returned error: VM Exception while processing transaction: revert at PromiEvent (C:\Users\lenovo\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\contract\lib\promievent.js:9:1)

What is the solution. Thank you.


pragma solidity ^0.5.12;

import "./customer.sol";
contract BankA{
  function pay() public returns(uint256){
    customer client=new customer();
    return address(client).balance;
  function() external payable{}



pragma solidity^0.5.12;
contract customer{
  function() external payable{}
  • What exactly is the point of this contract? Cause by calling pay() you create a new contract of type costumer and try sending it 1000 wei. Although, contract BankA has no balance. We need more information to help. – João Quintanilha Feb 6 '20 at 12:04
  • if you add a fallback function (function to transfer funds to BankA), it will have funds later to transfer to contract customer. – João Quintanilha Feb 6 '20 at 12:07

It looks as though it should work provided BankA has sufficient funds.

Keep in mind that this:


cannot work if it doesn't have sufficient funds to send 1000 to client.

Therefore, either invoke with {value: 1000} (or more), or use the fallback for a sinple transfer of some funds to BankA. Otherwise, it will fail for insufficient funds.

Hope it helps.

p.s. Consider address(client).transfer(msg.value); to forward whatever was received.

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