Transaction failed only with USDC

[0xmovses]

I have the following function. This function successfully transfers ERC20's, however, if the token is USDC the transaction fails.

If I don't specify a gasLimit I get , Cannot Estimate Gas error, if I do specify the gasLimit, as I am doing below, I simply get Transaction Failed.

I know that USDC uses the proxy pattern, the abi I'm passing in is an ERC20 abi. But I believe a normal ERC20 abi should work with USDC? Has anyone encountered this before? I'm on Polygon.

On the explorer it says Fail with error 'ERC20: transfer amount exceeds balance,'. For this transaction I transferred $0.01 and I have a balance of $1.86.

Tx : https://polygonscan.com/tx/0xc808feb904017f34a8ee37430bfe650e679fcdcb00edc967bfa265297afe7bda

And here's a successful tx using the same function but when the user selects an ERC20 that's not USDC https://polygonscan.com/tx/0x6b938e6616f29404de1530e3feb550c73bf85ba359de1eeec41fe022d01fc397

Thanks!

const sendTransaction = async () => {
        if (!provider) {
            alert("Please log in");
            return;
        } else {
            try {
                const signer = provider.getSigner();
                const amount = ethers.utils.parseUnits(amountToSend);                
                const contract = new ethers.Contract(tokenToSend, SocialToken.abi, signer);
                setLoading(true);
                const transaction = await contract.transfer(recipientAddress, amount, {gasLimit: 250000});  
                await transaction.wait();
                setLoading(false);
                setSuccessTransfer(true);
                getTokensBalAndPrice();
            } catch (error) {
                alert(error)
                setError(true)
            }  
          }    
    }

[zemse]

Hey @rvmelkonian, when you are working with various ERC20 tokens, you have to see if you are using proper decimals of an ERC20 token. Usually most of ERC20 tokens have decimals as 18. Hence the const amount = ethers.utils.parseUnits(amountToSend); defaults to 18. However USDC is having decimals as 6. So unknowingly you are trying to send 0.1 * 10**18 while you should be doing 0.1 * 10**6.

If you mention 6 as decimals (or dynamically query the decimals) then your tx should success.

const amount = ethers.utils.parseUnits(amountToSend, 6);`

[0xmovses]

This worked! Two things I learned here, that parseUnits accepts this second argument... and that ERC20's are not always bound to 18 decimals. So all I need to do is add in if statement to the function that checks if its USDC address and change the decimals if so.

Thank you for your speedy reply!

[Minhaj-ul-abidin]

@rvmelkonian you can get decimals from the contract like this

await contract.decimals()

avoiding any future errors because of decimals.