I'm starting on Smart Contract and ERC721 Collectible NFT and I'm using Ethers as Provider and Metamask to connect user.

I'm working on the Mint function from a React website, and it's working good when i'm the owner (so no need to send Eth) but when I try to implement it I receive an error:

index.ts:225 Uncaught (in promise) Error: overflow (fault="overflow", operation="BigNumber.from", value=70000000000000000, code=NUMERIC_FAULT, version=bignumber/5.5.0)
    at Logger.makeError (index.ts:225)
    at Logger.throwError (index.ts:237)
    at throwFault (bignumber.ts:358)
    at Function.from (bignumber.ts:249)
    at index.ts:263
    at Generator.next (<anonymous>)
    at fulfilled (index.ts:1)

This is my smart contract mint function:

    function mint(uint256 _mintAmount) public payable {
        uint256 supply = totalSupply();

        require(_mintAmount > 0);

        if (msg.sender != owner()) {
            require(msg.value >= cost * _mintAmount);
        for (uint256 i = 1; i <= _mintAmount; i++) {
            _safeMint(msg.sender, supply + i);

This is a working code (when I'm the owner of the contract)

await contract.mint(1);

but This one isn't working (even if i'm the owner or not)

await contract.mint(1, {value: cost});

This the documentation I tried to follow.

Metamask and Ethers as been connected using

connect(ethers.providers.Web3Provider, "any");

And the contract as been create (and signed) using:

const signer = (new ethers.providers.Web3Provider(window.ethereum)).getSigner();
const contract = new ethers.Contract(address, ABI, signer);

The cost variable is 0.07Eth (required amount to mint one NFT) and have been retrieved using the contract.cost function

const cost = parseInt((await contract.cost()).toString())

I really not understand how to fix it ? Thank you all for help ! :)

  • Can you post the solution to your issue please ? Mar 21, 2022 at 9:26
  • The answer under (by Kenzo Agada) resolve my question
    – Arthur
    Mar 22, 2022 at 13:41

1 Answer 1


The value parameter takes a string as input, so you don't need to convert the cost to an int. When you try to convert it it becomes too big to be a regular integer, and that's why you get the overflow.

So if you remove the parseInt from your cost, and just send it to mint as a string, it should work.

  • 1
    Ohh ! Thank you ! I tried it and it's a Javascript error and not a Ethers.js error you're right. But now I have to multiple it by the number of element to mint. How can I do it using string ? I'm tring to implement BigNumber like so const costBN = ethers.BigNumber.from(cost);
    – Arthur
    Dec 19, 2021 at 12:33
  • 1
    Making some research and I found it easly based on your answer. I'll use BigNumber.mul function
    – Arthur
    Dec 19, 2021 at 12:34

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