Problem when deploying contract using Remix on Testnet

Question

I tried to deploy a contract to Testnet with Remix (all Testnet return the same message) and I got this error:

Gas estimation errored with the following message (see below). The transaction execution will likely fail. Do you want to force sending?
Internal JSON-RPC error. { "code": -32000, "message": "gas required exceeds allowance (30000000) or always failing transaction" }

But when I tried to deploy it in BSC Mainnet everything works fine with no errors. Any suggestions?

this is the relevant code

contract artemis is Context, IERC20, Ownable {
    // ...

    constructor() public {
        _rOwned[_msgSender()] = _rTotal;

        IUniswapV2Router02 _uniswapV2Router =
            IUniswapV2Router02(0x05fF2B0DB69458A0750badebc4f9e13aDd608C7F);
        // Create a Pancakeswap pair for this new token
        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory())
            .createPair(address(this), _uniswapV2Router.WETH());

        // set the rest of the contract variables
        uniswapV2Router = _uniswapV2Router;

        //exclude owner and this contract from fee
        _isExcludedFromFee[owner()] = true;
        _isExcludedFromFee[address(this)] = true;

        emit Transfer(address(0), _msgSender(), _tTotal);
    }

    // ...
}

I upload the whole code here because its to long.

code

Please edit your question and share the source code of your contract. The "always failing transaction" is the more probable reason stated in the error message. — Petr Hejda, Apr 26 '21 at 07:19

score 7 · Answer 1 · edited Feb 26 '22 at 09:12

7

IUniswapV2Router02 _uniswapV2Router =
    IUniswapV2Router02(0x05fF2B0DB69458A0750badebc4f9e13aDd608C7F);

// Create a Pancakeswap pair for this new token
uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory())
    .createPair(address(this), _uniswapV2Router.WETH());

These lines in your constructor are trying to interact with a contract that exists on the mainnet. But you're on the testnet, where there's no contract on this address.

As stated in this post, the Pancake testnet router address is :

0xD99D1c33F9fC3444f8101754aBC46c52416550D1

So you need to replace the hardcoded address to this one.

edited Feb 26 '22 at 09:12

w3spi

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answered Apr 27 '21 at 07:43

Petr Hejda

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Thanks for your help...i was really stuck over here...can you please tell me if there is a way to change the maxTxAmount in my contract after i deployd . – marvin Apr 27 '21 at 16:54
@marvin I'm not sure what `maxTxAmount` you mean. If it's a variable with a setter function, you can execute the setter function to set the new value. If it's a constant (or a variable without a setter function), there's no way to change it, because the bytecode is immutable by design. – Petr Hejda Apr 27 '21 at 17:41
Thanks again for your answer.. uint256 public _maxTxAmount = 1000000000 * 10**6 * 10**9; i mean this...i dont think this si a constant...inside the contract it looks like this uint256 public _maxTxAmount = 5000000 * 10**6 * 10**9; and i need to make it uint256 public _maxTxAmount = 1000000000 * 10**6 * 10**9; Also is there another router address for ropsten network? Thanks in advance – marvin Apr 28 '21 at 03:17
In the case of your code (posted to the original question), you can affect the `_maxTxAmount` with the `setMaxTxPercent()` function. Mind that the function has the `onlyOwner` modifier, so you can execute it only from the `owner` address... Pancakeswap is an opensource, so there's pretty high chance there is another instance of their router, but I'm not aware of any. – Petr Hejda Apr 28 '21 at 07:17

Problem when deploying contract using Remix on Testnet

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