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  • I have already set my Subscriptions for Chainlink
  • Added consumer and subscription have sufficient Link as well
  • No Error occurs whenever I call the requestRandomWords function
  • fulfillment also updated on the chainlink subscriptions page
  • But still, the fulfillRandomWords function is not executing the code
  • tokenCounter is not updating its value

Chainlink Subscription Page

fulfillRandomWords(uint256 requestId, uint256[] memory randomWords)
    internal
    override
{
    tokenCounter = tokenCounter + 1;
    s_randomWords = randomWords;
    s_one_r = randomWords[0];
    address dogOwner = requestIdToSender[s_requestId];
    string memory tokenURI = requestIdToTokenURI[s_requestId];
    uint256 newItemId = tokenCounter;
    checkUri = tokenURI;
    //This newItemId should have to be a randomWords
    _safeMint(dogOwner, newItemId);
    _setTokenURI(newItemId, tokenURI);

    Breed breed = Breed(s_randomWords[0] % 3);
    tokenIdToBreenter code hereed[newItemId] = breed;
    requestIdToTokenId[s_requestId] = newItemId;

    emit FulfillEvent(tokenCounter, s_one_r, tokenURI);
    //randomResult = randomNumber;
}
Sulaman Khan
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  • Chainlink VRF V1 is working fine but V1 is deprecated now, So now I am using Chainlink VRF V2 but it is not executing the code in the given function. Although when I do the same thing in Remix it is working fine. – Sulaman Khan May 25 '22 at 22:47
  • Have you been able to figure out the issue? – Mutaz Jul 14 '22 at 04:42

3 Answers3

2

I'm running into the same issue. Randomness is generated for me but the callback to my consumer contract is failing. Please refer to this address to see the logs. The revert error is silent because VRFCoordinatorV2 is using call method to call rawFulfillRandomWords which calls fulfillRandomWords in my consumer contract. So all I'm getting is RandomWordsFulfilled event with success: false

How can I know the reason the call of my consumer fulfillRandomWords is failing? I'm emitting an event in the first line of my fulfillRandomWords but it is not being emitted. This means the callback from the coordinator is failing to call fulfillRandomWords without even executing the first line of fulfillRandomWords. In other words, there is nothing in my code is causing fulfillRandomWords call to fail because its first line (event emitting) is not being executed.

Mutaz Kasem
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Hi Sulaman

Two questions I guess! One: is fulfillRandomWords erroring or reverting?

Two, Is your s_randomWords state variable showing the random words passed into the callback? If that is updated then the callback is working but there may be some other issue with tokenCounter that is not possible to diagnose.

Can you also check the etherscan TX records for the VRF Coordinator calling your contract? If that has succeeded and the logs dont show errors then the callback is probably working as intended. You can access this Tx info from the history section of your VRF Subscription's URL. The screenshot you sent only shows the registered consumers and not the history of requests and events. Please check the Tx hash under History > Recent Requests and inspect for errors. The tx should record the call from an oracle providing the randomness to the VRF Coordinator (the coordinators address will show in the "To" field). If you open that Tx in etherscan and look at Internal TXs there should be one that is from the Coordinator to your smart contract (the callback) and that will also show the gas limit you set in your code etc.
If that call has no issue against it then the callback executed OK.

UPDATE 27 MAY 2022 OP posted the etherscan link which indicates (from the Internal Txns ) an "out of gas" error.

ZeusLawyer
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  • `fullfillRandomWords` is not reverting or throwing any error. `s_randomWords` state variable is not updating, and nothing in the `fulfillRandomWords` is updating. On the `etherscan` transaction is success – Sulaman Khan May 26 '22 at 14:23
  • you can view the transaction history from this link in `etherscan` [link](https://rinkeby.etherscan.io/address/0x30145fbc4b624c03bf3c596570a09fd6cf47bdb6) – Sulaman Khan May 26 '22 at 14:39
  • It may be easier to diagnose if you clearly state - your contract's address - which network you're on - the address of your VRF Coordinator which is in your contract etc But having said that, your etherscan link shows an out of gas error (click on the "Internal Txns" tab. You need to diagnose what's happening there. Somewhere along the chain of contract calls, the gas has run out. If you need further help please ensure you provide all the relevant details and chronology of the calls/txns so that people can trace the execution path. – ZeusLawyer May 27 '22 at 10:31
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I had similar problem, I fixed it by increasing Callback gas limit

mahyar
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