Section 4 Exercise/ Ethernaut Level 9 (King): transfer() and send() fails in attaining Kingship, but call() succeeds

[RichuAK]

I was trying to solve the King challenge in Ethernaut, but taking Kingship proved to be a bit tricky:

    // Transaction fails
    function takeTheThroneWithTransfer() public payable{
        payable(kingContractAddress).transfer(msg.value);
    }

    // Transaction fails
    function takeTheThroneWithSend() public payable {
        bool success = payable(kingContractAddress).send(msg.value);
        require(success, "Failed to send Ether");
    }

    // Transaction succeeds, attains Kingship
    function takeTheThroneWithCall() public payable{
        (bool success, ) = kingContractAddress.call{value: msg.value}("");
        require(success, "Failed to send Ether");
    }

I want to understand why this is the case, why transfer() and send() doesn't work but call() does.

Once Kingship was attained, I was able to submit the level successfully, solving the challenge.

I asked the same question on stackexchange as well.

Thanks in advance!

[johnsonstephan]

Good walkthrough here to help understand why transfer() and send() don't work but call() does - https://dev.to/nvn/ethernaut-hacks-level-9-king-12

[RichuAK]

Thank you so much! This was exactly what I was looking for! Couldn't find it myself after a lot of search!

[RichuAK]

@johnsonstephan

Feel free to answer the stackexchange question as well, or I'll answer it by tomorrow. Thanks a ton again!

[johnsonstephan]

I'm glad to hear it helped! I've answered on Stack as well -- https://ethereum.stackexchange.com/a/158985/130042