.getContractAddress() returning an incorrect address.

[adriandelgg]

Note: Not all sections may be relevant, but please be as thorough while remaining concise as possible. Remove this Notice and any sections that don't feel pertinent.

If you are unsure if something is a bug, start a thread in the "discussions" tab above..

Describe the bug
I have a Contract (A) that creates a Contract (B).

// Creates a new ERC20 contract
function createERC20(
  string memory _name,
  string memory _symbol,
  uint _mintAmount
) external returns (address newToken) {
  newToken = address(
	new ERC20Token(_name, _symbol, address(this), msg.sender, _mintAmount)
  );
  emit TokenCreated(newToken, _name, _symbol);
}

In the frontend, when I try to run getContractAddress() using tx.from & tx.nonce, I get an address back, but it's not the one that got created.

// Surprisingly this line returns the correct address BEFORE the contract is even accepted in MetaMask.
factoryContract.on('TokenCreated', e => console.log(e));

const tx = await factoryContract.createERC20(
  tokenName,
  tokenSymbol,
  mintAmount
);
// This returns an incorrect contract address.
const newTokenAddress = getContractAddress({
  from: tx.from,
  nonce: tx.nonce
});
await tx.wait();
			

Environment:
Hardhat, MetaMask, Ethers.js, Next.js

[ricmoo]

Are you trying to compute the address of contract A or contract B? For contract B you will need to use the nonce of contract A, not the EOA that sent the transaction.

[adriandelgg]

Are you trying to compute the address of contract A or contract B? For contract B you will need to use the nonce of contract A, not the EOA that sent the transaction.

Hi Richard, thanks for your reply! Just wanted to tell you real quick that I love the work that you do & I appreciate you!

My Contract A has a factory function that creates ERC20 tokens (Contract Bs). I want to get the contract address of the new Contract B that A created.

How would I do this? I'm unsure of how to get the nonce of Contract A, I was getting the nonce of the tx I was creating by calling Contract A.

[ricmoo]

Thanks! Glad to helps. :)

I haven’t actually ever done this myself, but every address’ nonce is stored in the state trie, and should be accessible using provider.getTransactionCount(contractA.address).

Generally I would recommend emitting an event in your ContractA that indicates the new address created, since then the transaction receipt can be queried more reliably, otherwise you might compute the new B’s address and someone might front-run you and sneak in ahead of you create that contract.

Using create2 also gives more control over the address being created, which does not take the sending nonce into account. But emitting an event is still recommended, if possible. Obviously sometimes this isn’t possible, such as counterfactual instantiating where the contract wont be deployed for quite some time (if ever).

Let me know if that works. :)

[adriandelgg]

Awesome! Thank you!

Something weird that I noticed that I'm not sure is the right behavior, but when I set up the event listener it logs the correct address before the transaction call is even executed/created. I actually put it in the 2nd code snippet. Is this proper behavior?

A workaround that I did to get the returned address was to use callStatic before calling the actual contract. I'm not sure if this is frowned upon.

const newTokenAddress = await factoryContract.callStatic.createERC20(
   tokenName,
   tokenSymbol.toUpperCase(),
   parseEther(mintAmount)
);
const tx = await factoryContract.createERC20(
   tokenName,
   tokenSymbol,
   parseEther(mintAmount)
);

[ricmoo]

Hmmm. I’m not totally sure what you mean by “before the call is even executed/created”.

Are you using Ganache? Because it does lots of strange things (since some operations that would be asynchronous are handled internally synchronously)?

Using callStatic is fine, but keep front running and consistency in mind; things can change on the blockchain between your callStatic and your transaction being mined. :)

[ricmoo]

(also, moving to discussions in case future people have related questions ;))

[theSkele]

I have similar issue related to contract deployment. Im using hardhat, and it seems to provide an address prior to submitting tx to blockchain. If i do contract.deployed() it permanently hangs. If i search address on polygonscan (or mumbai version) they are invalid/never used addresses. The weird thing is it only happens on Polygon networks (Mainnet and Mumbai)

const Token = await ethers.getContractFactory('TokenERC20');
const token = await Token.deploy();
console.log(await token.address + ' ' + await token.hash);
await token.deployed();
console.log('Token:' + token.address);
Running:
npx hardhat --network polygonMumbai run scripts/deploy.js
Results with:
account:0x1989d0CCCCA5530f48c3abbHIDINGmyADDRESSd95 0xc45E69180a61Cb5d634b187fE19304EFEf0Aa4fB undefined
and then hangs waiting for deployment

it creates a new address each time but no tx hash bc its not a valid transaction
I cannot find anything in issues that helps, been ongoing for about a month, and resorting to commenting here :) Thanks for any help

[zemse]

There are two issues, your tx nonce is 117 but your "latest" nonce is 57 and the tx is paying very less gasPrice. Looking at the explorer, txs paying 1 gwei are getting mined.

const token = await Token.deploy({
  gasPrice: ethers.utils.parseUnits('2', 'gwei')
  nonce: 57 // or await Token.signer.getTransactionCount('latest')
})

[theSkele]

Thank you, you solved my problem. Do you happen to know why ethers has been setting the incorrect nonce? Am I supposed to be managing this every time?

[zemse]

By default ethers uses getTransactionCount('pending') to avoid unnecessary transaction replacement. This particularly becomes a problem when a transaction becomes stuck (for any reason mostly low gasPrice).

[theSkele]

Ahh understood. Thanks again, I truly appreciate the help mate!

[zemse]

You're welcome! :)