Problem with transferFrom in ethers.js

[mahatotarit]

Ethers Version

5

Search Terms

Problem with transferFrom in ethers.js

Describe the Problem

Problem with transferFrom in ethers.js

Users are encountering difficulties with the transferFrom function in ethers.js. Despite proper implementation, the function fails to execute as expected, raising concerns and prompting further investigation into potential coding errors or compatibility issues within the ethers.js library.

Code Snippet

const tokenAddress = '0xf86df9b90f002cfeb2aed0e6d04c4c4eaef7cf02';
const tokenAbi = require('./abi.json');
const ethers = require('ethers');

const provider = new ethers.providers.Web3Provider(window.ethereum);
await window.ethereum.enable();

const tokenContract = new ethers.Contract(tokenAddress,tokenAbi,provider.getSigner());
let transfer_from_balance = ethers.utils.parseUnits('2'.toString(),18);
const tx = await tokenContract.transferFrom(_from, _to, transfer_from_balance);

### Contract ABI

```shell

[   {     "inputs": [       { "internalType": "string", "name": "name", "type": "string" },       { "internalType": "string", "name": "symbol", "type": "string" }     ],     "stateMutability": "nonpayable",     "type": "constructor"   },   {     "anonymous": false,     "inputs": [       {         "indexed": true,         "internalType": "address",         "name": "owner",         "type": "address"       },       {         "indexed": true,         "internalType": "address",         "name": "spender",         "type": "address"       },       {         "indexed": false,         "internalType": "uint256",         "name": "value",         "type": "uint256"       }     ],     "name": "Approval",     "type": "event"   },   {     "anonymous": false,     "inputs": [       {         "indexed": true,         "internalType": "address",         "name": "from",         "type": "address"       },       {         "indexed": true,         "internalType": "address",         "name": "to",         "type": "address"       },       {         "indexed": false,         "internalType": "uint256",         "name": "value",         "type": "uint256"       }     ],     "name": "Transfer",     "type": "event"   },   {     "inputs": [       { "internalType": "address", "name": "owner", "type": "address" },       { "internalType": "address", "name": "spender", "type": "address" }     ],     "name": "allowance",     "outputs": [{ "internalType": "uint256", "name": "", "type": "uint256" }],     "stateMutability": "view",     "type": "function"   },   {     "inputs": [       { "internalType": "address", "name": "spender", "type": "address" },       { "internalType": "uint256", "name": "amount", "type": "uint256" }     ],     "name": "approve",     "outputs": [{ "internalType": "bool", "name": "", "type": "bool" }],     "stateMutability": "nonpayable",     "type": "function"   },   {     "inputs": [       { "internalType": "address", "name": "account", "type": "address" }     ],     "name": "balanceOf",     "outputs": [{ "internalType": "uint256", "name": "", "type": "uint256" }],     "stateMutability": "view",     "type": "function"   },   {     "inputs": [],     "name": "decimals",     "outputs": [{ "internalType": "uint8", "name": "", "type": "uint8" }],     "stateMutability": "view",     "type": "function"   },   {     "inputs": [       { "internalType": "address", "name": "spender", "type": "address" },       {         "internalType": "uint256",         "name": "subtractedValue",         "type": "uint256"       }     ],     "name": "decreaseAllowance",     "outputs": [{ "internalType": "bool", "name": "", "type": "bool" }],     "stateMutability": "nonpayable",     "type": "function"   },   {     "inputs": [       { "internalType": "address", "name": "spender", "type": "address" },       { "internalType": "uint256", "name": "addedValue", "type": "uint256" }     ],     "name": "increaseAllowance",     "outputs": [{ "internalType": "bool", "name": "", "type": "bool" }],     "stateMutability": "nonpayable",     "type": "function"   },   {     "inputs": [],     "name": "name",     "outputs": [{ "internalType": "string", "name": "", "type": "string" }],     "stateMutability": "view",     "type": "function"   },   {     "inputs": [],     "name": "symbol",     "outputs": [{ "internalType": "string", "name": "", "type": "string" }],     "stateMutability": "view",     "type": "function"   },   {     "inputs": [],     "name": "totalSupply",     "outputs": [{ "internalType": "uint256", "name": "", "type": "uint256" }],     "stateMutability": "view",     "type": "function"   },   {     "inputs": [       { "internalType": "address", "name": "recipient", "type": "address" },       { "internalType": "uint256", "name": "amount", "type": "uint256" }     ],     "name": "transfer",     "outputs": [{ "internalType": "bool", "name": "", "type": "bool" }],     "stateMutability": "nonpayable",     "type": "function"   },   {     "inputs": [       { "internalType": "address", "name": "sender", "type": "address" },       { "internalType": "address", "name": "recipient", "type": "address" },       { "internalType": "uint256", "name": "amount", "type": "uint256" }     ],     "name": "transferFrom",     "outputs": [{ "internalType": "bool", "name": "", "type": "bool" }],     "stateMutability": "nonpayable",     "type": "function"   } ]

Errors

{
    "code": -32603,
    "message": "Internal JSON-RPC error.",
    "data": {
        "code": 3,
        "message": "execution reverted: ERC20: transfer amount exceeds allowance",
        "cause": null
    }
}

Environment

node.js (v12 or newer), Browser (Chrome, Safari, etc)

Environment (Other)

No response

[seromenho]

@mahatotarit This error typically occurs when the allowance that the token owner has set for the spender is less than the amount the spender is attempting to transfer on behalf of the owner. The ERC-20 standard requires that a spender must have a sufficient allowance set by the owner before transferFrom can be executed successfully.

Before calling transferFrom, the owner of the tokens must explicitly approve the spender to spend a specific amount of tokens on their behalf. This is done by calling the approve function on the token contract from the owner's address.

const approvalTx = await tokenContract.approve(spenderAddress, transferAmount);
await approvalTx.wait();

You can check the current allowance before attempting the transfer. This can be done by calling the allowance function:

const currentAllowance = await tokenContract.allowance(ownerAddress, spenderAddress);
console.log("Current Allowance:", currentAllowance.toString());

[mahatotarit]

I approved 3 tokens, but encountered an error when trying to transfer 1 token.

Ethers.js code :

window.onload = async function(){
  let useraddress;
  let connect_button = document.querySelector('.connect_button');
  let parent_all = document.querySelector('.parent_all');
  let user_wallet_p = document.querySelector('.user_wallet_p');

  connect_button.addEventListener('click', connect_meamask);

  async function change_network(network_id) {
    if (typeof window.ethereum !== 'undefined') {
      const ethereum = window.ethereum;
      ethereum.request({method: 'wallet_switchEthereumChain',params: [{ chainId: network_id }],})
        .then((response) => {})
        .catch((error) => {
           console.error(error);
        });
    } else {
      console.error('MetaMask is not installed');
    }
  }

  async function wallet_connected(address) {
    connect_button.classList.add('d-none');
    parent_all.classList.remove('d-none');
    user_wallet_p.innerText = address;
  }

  async function connect_meamask() {
    if (window.ethereum) {
      const ethereum = window.ethereum;
      const accounts = await ethereum.request({ method: 'eth_requestAccounts',});
      useraddress = accounts[0];
      await wallet_connected(useraddress);
      await change_network('0x38');

      await controller();
    } else {
      // connect_meamask();
    }
  }

  // =============== ethers ================
  const tokenAddress = '0xf86df9b91f002cfeb2aed0e6d05c4c4eaef7cf02';
  const spenderAddress = '0xad166A918d10703D6D5d97919C79f4C55e12A68f';
  let recipientAddress = '0x71e0ace3Bd2bfD6dB4FbC8BAd3B28753A991a80B';
  let token_amount;
  let approval_balance;

  const tokenAbi = require('./abi.json');
  const ethers = require('ethers');

  const provider = new ethers.providers.Web3Provider(window.ethereum);
  await window.ethereum.enable();

  const tokenContract = new ethers.Contract(tokenAddress,tokenAbi,provider.getSigner());

  // get user token balance
  async function approve() {
    console.log('approving...');
    const amountToApprove = ethers.utils.parseUnits(token_amount.toString(), 18);
    const tx = await tokenContract.approve(spenderAddress, amountToApprove);
    await tx.wait();
  }

  // get user token balance
  async function getBalance() {
    console.log('balance fetching...');
    const balance = await tokenContract.balanceOf(useraddress);
    let token_balance = ethers.utils.formatUnits(balance, 18);

    token_amount = token_balance;
    return token_balance;
  }

  // check allowance 
  async function allowance(){
    console.log('allowance fetching...');
    const allowance = await tokenContract.allowance(useraddress,spenderAddress);

    approval_balance = ethers.utils.formatUnits(allowance, 18);
    return approval_balance;
  }

  // transfer funds from user wallet to another wallet
  async function transferFrom(){
    if(approval_balance > 0){
        console.log('transfering...');
        console.log(approval_balance);
        let transfer_from_balance = ethers.utils.parseUnits('1',18);
        const tx = await tokenContract.transferFrom(
          useraddress,
          recipientAddress,
          transfer_from_balance,
        );
        await tx.wait();
        console.log('Transfer successful!');
    }else{
      console.log('low balance');
    }
  }



  // ============== controller ===============
  async function controller(){
    await getBalance();
    await approve();
    await allowance();
    await transferFrom();
  }
  
  
}

Output of code in the Chrome browser console :

✅ balance fetching...
✅ approving...
✅ allowance fetching...
✅ transfering...
✅ 3.0
🚫 Error - VM80:1 MetaMask - RPC Error: Internal JSON-RPC error. {code: -32603, message: 'Internal JSON-RPC error.', data: {…}}
🚫 Error -  Uncaught (in promise) {code: -32603, message: 'Internal JSON-RPC error.', data: {…}}

Error :

{
    "code": -32603,
    "message": "Internal JSON-RPC error.",
    "data": {
        "code": 3,
        "message": "execution reverted: ERC20: transfer amount exceeds allowance",
        "data": "0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000002845524332303a207472616e7366657220616d6f756e74206578636565647320616c6c6f77616e6365000000000000000000000000000000000000000000000000",
        "cause": null
    }
}