Insufficient Liquidity after adding liquidity on Sepolia Uniswap V2

Question

I created a token "TestMe" with 2 million tokens (18dec), minting the deployer address the whole stack. I used the "addLiquidityETH" function provided by uniswap router to add 500k tokens and 0.5 ETH. When I am using the deployer wallet to place a trade via uniswap V2 app on sepolia (Buy/sell) with a small amount of token , I always receive the error message "Insufficient Liquidity".

Here is the link to the contract where you can see the AddLiquidity tx: https://sepolia.etherscan.io/address/0x6161B4E0AE26f2aB2fAC2660B73F7aaFD44FfE72

Here my code if necessary: Deploy script:

// SPDX-License-Identifier: MIT
const fs = require("fs");

async function main() {
    
    async function deploy() {
        console.log("Starting deployment script...");
        const [deployer] = await ethers.getSigners();
        console.log("Signer fetched:", deployer.address);
      
        const TestMe = await ethers.getContractFactory("TestMe", deployer);

        const testMe = await TestMe.deploy();
        console.log("testMe contract address:", testMe.target);

        //save address from contract
        fs.writeFileSync("deployedYeetAddress.json", JSON.stringify({ address: testMe.target }));
        console.log("testMe contract address saved to deployedtestMeAddress.json");

        await testMe.approve(testMe.target, ethers.parseUnits("500000", 18));
        await testMe.addLiquidity(ethers.parseUnits("500000", 18), {
            value: ethers.parseEther("0.1")
        });
        
    }
    await deploy();

}

contract:

// SPDX-License-Identifier: MIT
pragma solidity 0.8.24;

import "lib/openzeppelin-contracts/contracts/token/ERC20/ERC20.sol";
import "lib/openzeppelin-contracts/contracts/access/Ownable.sol";
import "lib/openzeppelin-contracts/contracts/security/ReentrancyGuard.sol";
import "interfaces/uniswap-v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "uniswap-v2-core/contracts/interfaces/IUniswapV2Pair.sol";
import "uniswap-v2-core/contracts/interfaces/IUniswapV2Factory.sol";

contract TestMe is ERC20, Ownable{
    IUniswapV2Pair public immutable uniswapV2Pair;
    IUniswapV2Router02 public immutable uniswapV2Router;
    constructor() ERC20('TestMe','TestMe COIN'){
        _mint(msg.sender, 2000000 * 10**18);
        uniswapV2Router = IUniswapV2Router02(0xC532a74256D3Db42D0Bf7a0400fEFDbad7694008); // must be exchanged for mainnet!!!
        uniswapV2Pair = IUniswapV2Pair(
            IUniswapV2Factory(uniswapV2Router.factory()).createPair(address(this), uniswapV2Router.WETH())
        );
    }

    function addLiquidity(uint256 tokenAmount) public payable onlyOwner {
        _transfer(owner(), address(this), tokenAmount);
        this.approve(address(uniswapV2Router), tokenAmount);
        uniswapV2Router.addLiquidityETH{value: msg.value}(address(this), tokenAmount, 0, 0, owner(), block.timestamp);
    }
}

Answer 1

I didn't think the front end was connected to the smart contracts on the test net. You can still use the router to test, just swap via the explorer:

• https://sepolia.etherscan.io/address/0xc532a74256d3db42d0bf7a0400fefdbad7694008#writeContract

• Click connect to web3

• Scroll to 9. swapETHForExactTokens (or 10. swapExactETHForTokens)

• Enter a value to pay in eth, with the format of using a decimal point, for example 1.0 for 1

• Input an amountOut (or amountOutMin), but this time no decimal, instead * 10 ** decimals the token has, for example 1000000000000000000, for 1

• • Try anything greater than 0 for the test.

• path should be weth and your token

['0x7b79995e5f793A07Bc00c21412e50Ecae098E7f9','0x6161B4E0AE26f2aB2fAC2660B73F7aaFD44FfE72']

• to should be your address or your contract, wherever the destination is.

• deadline is some unix timestamp in the future.

• • 2*10**10 is distant.

• Click write

• Confirm in wallet.

example swap: - https://sepolia.etherscan.io/tx/0x37c0026e736dbe4e4572f0507a5cb4a7485ca00707f70a12d515b98a95258aff

edit to add a requested example:

RPC = 'https://rpc2.sepolia.org'
CHAIN_ID = 0xaa36a7

from web3 import Web3 as w, HTTPProvider as hp
w3 = w(hp(RPC))

from os import getenv
from dotenv import load_dotenv
load_dotenv()
KEY = getenv('KEY')
EOA = getenv('ADD')
#----------------------

ROUTER = '0xC532a74256D3Db42D0Bf7a0400fEFDbad7694008'
NATIVE = '0x7b79995e5f793A07Bc00c21412e50Ecae098E7f9'
TOKEN = '0x6161B4E0AE26f2aB2fAC2660B73F7aaFD44FfE72'

ROUTER_ABI = '''
[{"inputs":[{"internalType":"address","name":"_factory","type":"address"},{"internalType":"address","name":"_WETH","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"inputs":[],"name":"WETH","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"tokenA","type":"address"},{"internalType":"address","name":"tokenB","type":"address"},{"internalType":"uint256","name":"amountADesired","type":"uint256"},{"internalType":"uint256","name":"amountBDesired","type":"uint256"},{"internalType":"uint256","name":"amountAMin","type":"uint256"},{"internalType":"uint256","name":"amountBMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"addLiquidity","outputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"amountB","type":"uint256"},{"internalType":"uint256","name":"liquidity","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amountTokenDesired","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"addLiquidityETH","outputs":[{"internalType":"uint256","name":"amountToken","type":"uint256"},{"internalType":"uint256","name":"amountETH","type":"uint256"},{"internalType":"uint256","name":"liquidity","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"factory","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"reserveIn","type":"uint256"},{"internalType":"uint256","name":"reserveOut","type":"uint256"}],"name":"getAmountIn","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"reserveIn","type":"uint256"},{"internalType":"uint256","name":"reserveOut","type":"uint256"}],"name":"getAmountOut","outputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"}],"name":"getAmountsIn","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"}],"name":"getAmountsOut","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"reserveA","type":"uint256"},{"internalType":"uint256","name":"reserveB","type":"uint256"}],"name":"quote","outputs":[{"internalType":"uint256","name":"amountB","type":"uint256"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"address","name":"tokenA","type":"address"},{"internalType":"address","name":"tokenB","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountAMin","type":"uint256"},{"internalType":"uint256","name":"amountBMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"removeLiquidity","outputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"amountB","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"removeLiquidityETH","outputs":[{"internalType":"uint256","name":"amountToken","type":"uint256"},{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"removeLiquidityETHSupportingFeeOnTransferTokens","outputs":[{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bool","name":"approveMax","type":"bool"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"removeLiquidityETHWithPermit","outputs":[{"internalType":"uint256","name":"amountToken","type":"uint256"},{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bool","name":"approveMax","type":"bool"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"removeLiquidityETHWithPermitSupportingFeeOnTransferTokens","outputs":[{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"tokenA","type":"address"},{"internalType":"address","name":"tokenB","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountAMin","type":"uint256"},{"internalType":"uint256","name":"amountBMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bool","name":"approveMax","type":"bool"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"removeLiquidityWithPermit","outputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"amountB","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapETHForExactTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactETHForTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactETHForTokensSupportingFeeOnTransferTokens","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForETH","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForETHSupportingFeeOnTransferTokens","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForTokensSupportingFeeOnTransferTokens","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMax","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapTokensForExactETH","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMax","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapTokensForExactTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"stateMutability":"payable","type":"receive"}]
'''

dex = w3.eth.contract(address=ROUTER, abi=ROUTER_ABI)

swap = dex.functions.swapExactETHForTokens(
  # don't put value here this time that is only for explorers, put it in the transaction parameters
  0,
  ['0x7b79995e5f793A07Bc00c21412e50Ecae098E7f9','0x6161B4E0AE26f2aB2fAC2660B73F7aaFD44FfE72'],
  EOA,
  2*10**10
).build_transaction({
  'value': 1000000000000000,
  'from': EOA,
  'chainId': CHAIN_ID,
  'gas': 500000,
  'maxFeePerGas': w3.eth.gas_price * 2,
  'maxPriorityFeePerGas': w3.eth.max_priority_fee * 2,
  'nonce': w3.eth.get_transaction_count(EOA)
})

w3.eth.call(swap)

# helpers
def sign_tx(tx, key):
  sig = w3.eth.account.sign_transaction
  signed_tx = sig(tx, private_key=key)
  return signed_tx

def send_tx(signed_tx):
  w3.eth.send_raw_transaction(signed_tx.rawTransaction)
  tx_hash = w3.to_hex(w3.keccak(signed_tx.rawTransaction))
  return tx_hash

def main():
  ('[-] Attempting swap...')
  tx_hash = send_tx(sign_tx(swap, KEY))
  receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
  print (f'[>] Hash of attempt: {tx_hash}\n[>] {receipt}')

if __name__ == '__main__':
  main()