I'm trying to migrate a contract into a ganache chain. It needs to use Oraclize - in the end, the plan is to have a private chain using Oraclize via ethereum-bridge. However, truffle migrate fails with the message:

Error:  *** Deployment Failed ***

"VatValidator" hit a require or revert statement somewhere in its constructor. Try:
   * Verifying that your constructor params satisfy all require conditions.
   * Adding reason strings to your require statements.

    at /Users/alex/.nvm/versions/node/v10.15.3/lib/node_modules/truffle/build/webpack:/packages/truffle-deployer/src/deployment.js:364:1
    at process._tickCallback (internal/process/next_tick.js:68:7)

Here's the contract:

pragma solidity >=0.5.0;
import "./Oraclize.sol";

contract VatValidator is usingOraclize {

    string public isValid;

    event newOraclizeQuery(string description);
    event newVATResult(string price);

    constructor() public {
        // oraclize_setProof(proofType_TLSNotary | proofStorage_IPFS);
        OAR = OraclizeAddrResolverI(0x6f485C8BF6fc43eA212E93BBF8ce046C7f1cb475);

    function __callback(bytes32 myid, string memory result, bytes memory proof) public {
        require (msg.sender != oraclize_cbAddress());
        isValid = result;
        emit newVATResult(isValid);

    function update() public payable {

        emit newOraclizeQuery("Oraclize query was sent, standing by for the answer.");

        oraclize_query("URL", "json(http://url.com).valid",'{"arg1":"abc", "arg2":"def"}');


I don't have any revert or assert statements at all in the constructor however.

  • Hi there. I haven't played around with Oraclize for a while, but from what I remember you'll need to use ethereum-bridge to give the Oraclize contract/API something to talk to. (github.com/oraclize/ethereum-bridge) That's assuming you haven't done so already. Apr 5, 2019 at 17:23
  • Actually that's my plan, just added in the question. Still no difference.
    – Alex
    Apr 5, 2019 at 17:24
  • That's annoying. Does it work if you use the Javascript VM in Remix, together with the Oraclize plugin (under Settings)? Apr 5, 2019 at 17:27
  • @Richard Yes, that works
    – Alex
    Apr 5, 2019 at 18:12
  • Do you have the bridge up and running before you try and migrate?
    – gskapka
    Apr 10, 2019 at 14:05


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