UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT

[LordReya]

I tried to look it up online, but every time I try to estimate price, this error comes up. What exactly does it mean? How do you fix it?

The error occurs every time I try to estimate the price from diffrent dexes with this script here. Trying to create a arbitrage bot. I suppose it could be that I need WETH or WMATIC to do the transaction. I'm working on the polygon mainnet btw. The script works well and does it's job, but everytime before it actually performs the trade I get this error. I have enough base asset and gas fees setup to perform the transaction. Really weird that it still gives me timeouts and then this error.

dotEnvConfig();
import * as UniswapV2Router from "../../../abis/IUniswapV2Router02.json";
import { getBigNumber } from "../../../utils";

const maticProvider = new ethers.providers.JsonRpcProvider(
  process.env.ALCHEMY_POLYGON_RPC_URL
);

/**
 *
 * @param tokenIn address of token to convert from
 * @param tokenOut address of token to convert to
 * @param amountIn amount of token to convert from
 * @param routerAddress router address
 * @returns
 */
export const getPriceOnUniV2 = async (
  tokenIn: string,
  tokenOut: string,
  amountIn: BigNumber,
  routerAddress: string
): Promise<BigNumber> => {
  const V2Router = new ethers.Contract(
    routerAddress,
    UniswapV2Router.abi,
    maticProvider
  );
  const amountsOut = await V2Router.getAmountsOut(amountIn, [
    tokenIn,
    tokenOut,
  ]);
  if (!amountsOut || amountsOut.length !== 2) {
    return getBigNumber(0);
  }
  return amountsOut[1];
};

[othaime-en]

Hey @LordReya you need to provide more context about your error so that we may understand what may lead to the error you encountered.

[LordReya]

Hey @othaime-en ! Sorry I was so focused that I completly forgot to add in the context. The error occurs every time I try to estimate the price from diffrent dexes with this script here. Trying to create a arbitrage bot. I suppose it could be that I need WETH or WMATIC to do the transaction. I'm working on the polygon mainnet btw. The script works well and does it's job, but everytime before it actually performs the trade I get this error. I have enough base asset and gas fees setup to perform the transaction. Really weird that it still gives me timeouts and then this error.

import { BigNumber, ethers } from "ethers";
dotEnvConfig();
import * as UniswapV2Router from "../../../abis/IUniswapV2Router02.json";
import { getBigNumber } from "../../../utils";

const maticProvider = new ethers.providers.JsonRpcProvider(
  process.env.ALCHEMY_POLYGON_RPC_URL
);

/**
 *
 * @param tokenIn address of token to convert from
 * @param tokenOut address of token to convert to
 * @param amountIn amount of token to convert from
 * @param routerAddress router address
 * @returns
 */
export const getPriceOnUniV2 = async (
  tokenIn: string,
  tokenOut: string,
  amountIn: BigNumber,
  routerAddress: string
): Promise<BigNumber> => {
  const V2Router = new ethers.Contract(
    routerAddress,
    UniswapV2Router.abi,
    maticProvider
  );
  const amountsOut = await V2Router.getAmountsOut(amountIn, [
    tokenIn,
    tokenOut,
  ]);
  if (!amountsOut || amountsOut.length !== 2) {
    return getBigNumber(0);
  }
  return amountsOut[1];
};

[LordReya]

@krakxn Do you maybe have a clue?

[krakxn]

Sorry, did not see the notification :(

[LordReya]

Sorry, did not see the notification :(

All good no worries!

[LordReya]

I fixed the problem myself. You need WETH or WMATIC depending on the network to interact with Smartcontracts on the Mainnet.

[othaime-en]

Glad it worked out for you. This has been bugging me these past few days. Sorry I couldn't help.

[krakxn]

When on a different network (chain), you need to use wrapped tokens of the native token; e.g. WETH on Uniswap--this is evident from Uniswap's liquid swap as well.

[LordReya]

@othaime-en No worries! Let me know if the bug is still there. Happy to help you :)

[LordReya]

When on a different network (chain), you need to use wrapped tokens of the native token; e.g. WETH on Uniswap--this is evident from Uniswap's liquid swap as well.

I saw that polycat and 1Inch API use WETH instead of WMATIC when you try to work with some of their smartcontracts even on the Polygon network. I'd say it depends on the exchange, dex, etc and the smartcontract you are working with. However, WMATIC is totally fine for UniV2 and V3 for Poly Mainnet.