im new in web3js and i got a problem. Would be nice, if you could help me. Ive been trying to solve it myself for days...

Im trying to simulate a buy transaction (after its working i will do the sell part), to check if buys (and sells) would success. but im getting this error: "Error: Returned error: execution reverted: PancakeLibrary: INSUFFICIENT_INPUT_AMOUNT"

but i have enough bnb in my wallet. What am i doing wrong? here is my code:

var Web3 = require("web3");
var web3 = new Web3(new Web3.providers.HttpProvider('https://bsc-dataseed.binance.org/'));

var panabi = JSON.parse(fs.readFileSync('panabi.json', 'utf-8'));

var MY_ADDRESS = "0x....";
var WBNB_ADDRESS = "0xbb4cdb9cbd36b01bd1cbaebf2de08d9173bc095c"; // spend

var TokenAddress = "0x8076c74c5e3f5852037f31ff0093eeb8c8add8d3"; //Token to buy
var PANCAKESWAP_ROUTER_ADDRESS = "0x10ED43C718714eb63d5aA57B78B54704E256024E";

let contract = new web3.eth.Contract(panabi, PANCAKESWAP_ROUTER_ADDRESS);

// First step: Execute a buy for specific token. Since I don't want to send that 
// transaction to blockchain, I'm just calling that function and see its result

var tx = new web3.eth.getTransactionCount(MY_ADDRESS, (err, result) => { console.log(result) });

var batch = new web3.eth.BatchRequest();
var callback = batch.add(
        web3.utils.toHex(0), //slippage
        [WBNB_ADDRESS, TokenAddress],
        web3.utils.toHex(Math.round(Date.now() / 1000) + 60 * 20)
            gasLimit: web3.utils.toHex(2000000),
            gasPrice: web3.utils.toHex(web3.utils.toWei('7', 'gwei')),
            value: web3.utils.toHex(web3.utils.toWei('0.01', 'ether')),
            nonce: web3.utils.toHex(tx)
        }, 'latest', callback)
console.log(callback); // this line should log response of your query```

1 Answer 1


As you can see from the pancakeswap contract code, this error is triggered by this:

require(amountIn > 0, 'PancakeLibrary: INSUFFICIENT_INPUT_AMOUNT');

The contract thinks that the amount that you are trying to swap is 0. Your transaction does include a value of 0.01 BNB to swap and this is what the contract should use as amountIn. I am not sure why it sees it as 0...

Maybe try replacing:

value: web3.utils.toHex(web3.utils.toWei('0.01', 'ether')),


value: "10000000000000000",
  • unfortunately its not working. do you have another idea how to simulate a buy on the mainnet? Nov 29, 2021 at 4:07
  • Maybe that batch requests cannot pass a value... Instead of doing a batch request, try a single call to the contract like so: web3js.readthedocs.io/en/v1.5.0-rc.0/…
    – Undead8
    Nov 29, 2021 at 18:39
  • Batch requests in web3js are kind of buggy...
    – Undead8
    Nov 29, 2021 at 18:39

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