I'm trying to use Chainlink's VRF to produce a random number. I've followed guides and produced a basic contract to do this, but getRandomNumber() isn't working. I am using the Sepolia test network.

//SPDX-License-Identifier: MIT
pragma solidity >=0.8.17;
import "@chainlink/contracts/src/v0.8/VRFConsumerBase.sol";

contract Test is VRFConsumerBase {
    uint256 public _randomSeed;
    bytes32 internal keyHash;

     * https://docs.chain.link/vrf/v2/subscription/supported-networks
     * Network: Sepolia
     * LINK: 0x779877A7B0D9E8603169DdbD7836e478b4624789
     * VRF: 0x8103B0A8A00be2DDC778e6e7eaa21791Cd364625
    constructor(address _vrfCoordinator, address _link)
        VRFConsumerBase(_vrfCoordinator, _link) {
            keyHash = 0x474e34a077df58807dbe9c96d3c009b23b3c6d0cce433e59bbf5b34f823bc56c;

    function getRandomNumber()
        returns (bytes32) {
            uint256 _fee = 25 * (10 ** 16); // 0.25 LINK;
            if (LINK.balanceOf(address(this)) < _fee) {
                revert("Inadequate Link to fund this transaction");
            return requestRandomness(keyHash, _fee);

    function fulfillRandomness(bytes32 /*requestId*/, uint256 randomness)
        override {
           _randomSeed = randomness;

    function withdraw()
    external {
        bool success = LINK.transfer(msg.sender, LINK.balanceOf(address(this)));
        if (!success) {
            revert("withdrawLINK() PaymentFailure1");

When I try calling/transacting getRandomNumber() I get the following revert:

transact to Test.getRandomNumber errored: execution reverted
  "originalError": {
    "code": 3,
    "data": "0x8129bbcd",
    "message": "execution reverted"

The data of the error corresponds to "InvalidCalldata()". I believe the error is coming from: https://github.com/smartcontractkit/chainlink/blob/develop/contracts/src/v0.8/VRFCoordinatorV2.sol (line 664)

However, I have no idea why this error is popping up. I followed instructions online creating this contract, but it doesn't work. If anyone could reproduce this and/or even fix and point out my error, I'd greatly appreciate it. Thank you.

1 Answer 1


You're interacting with VRF V2 the way you should be interacting with VRF v1. Either use the V1 contracts (They arent deployed on Sepolia though, but they exist on goerli amongst others (see https://docs.chain.link/vrf/v1/supported-networks)) or make your contract work with v2 ( https://docs.chain.link/vrf/v2/introduction is a good starting point)

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