Gas estimation on simple function fails

[JCaraballo113]

Describe the bug

So I have this function

function unstake(uint256 amount) public {
        require(_stakedAmounts[msg.sender] != 0, "Has not staked");
        require(_stakedAmounts[msg.sender] - (_unstakedAmounts[msg.sender] + amount) >= 0, "Cannot unstake more than total staked amount");
        _unstakedAmounts[msg.sender] += amount;
        emit Unstaked(msg.sender, amount);
        emit TotalUnstaked(msg.sender, _unstakedAmounts[msg.sender]);
    }

Which is pretty simple and it used to work just fine with useDapp on the GOERLI network. But after the merge on goerli or some kind of update I keep getting the following error:

Error: cannot estimate gas; transaction may fail or may require manual gas limit

This function has been the same for over 3 months and it used to work fine using the useContractFunction hook. It was just recently that this error started happening. I have confirmed the issue is within useDapp and not my smart contract code because you can call the unstake function on etherscan directly without any issues.

To Reproduce No idea how to reproduce since I don't know what actually causes it.

Config:

const readConfig =
    process.env.POLYGON_CHAIN_ID === '80001'
        ? {
              [Mumbai.chainId]: process.env.POLYGON_URL || '',
              [SkaleChain.chainId]: process.env.SKALE_URL || '',
          }
        : {
              [Polygon.chainId]: process.env.POLYGON_URL || '',
              [SkaleChain.chainId]: process.env.SKALE_URL || '',
          };

const dappConfig: Config = {
    networks: [...DEFAULT_SUPPORTED_CHAINS, SkaleChain],
    readOnlyUrls: {
        [Goerli.chainId]: process.env.INFURA_NETWORK || '',
        ...readConfig,
    },
};

Software versions

• useDapp version : 1.1.5
• Package manager : npm
• Node version: 16.16.0

Additional context

[rzadp]

@JCaraballo113 It started happening recently - does it happen always, or randomly? There were no useDapp package upgrades in the meantime?

Trying to narrow down the problem.

[rzadp]

Does the error happen only on one chain - Goerli? Or does it happen on all other chains as well?

[JCaraballo113]

@rzadp sorry I was travelling!. It happens always on Goerli at least. I have not tried with other chains. Unless useDapp has gone past 1.1.5 then there are no updates

[rzadp]

I'm trying to reproduce it. On Goerli, with a simple WETH contract.

Example transaction initiated from Etherscan UI: https://goerli.etherscan.io/tx/0x319ad57b4c6d07f4ddd264f512c73ead8d097ba7ec0cd301223bb9302152e175

Example transaction initiated from useDApp UI (no gasLimitBufferPercentage): https://goerli.etherscan.io/tx/0xb4b903b3271bcf4d04d380ffaa09039b0ce275d07872ef2db0015be6f4b1665d

---

So the transaction uses 98% of estimated gas, and is mined successfully. I have also tested a useDApp version from 3 months ago before any changes to gas estimation we did recently - works the same.

So, no success in reproduction so far.

@JCaraballo113 Perhaps you actually do need to set the gasLimitBufferPercentage? Can you set it to 10 for example (will add 10% on top of estimated gas limit) and see if that helps?

Also, since your contract is deployed on Goerli testnet, are you able to grant me some rights / stake to it so that I could try to reproduce it myself?

[JCaraballo113]

@rzadp all you need to stake/unstake is some of our tokens. If you can plop your wallet here I can send you some and then you will be able to stake/unstake yourself

[rzadp]

@rzadp all you need to stake/unstake is some of our tokens. If you can plop your wallet here I can send you some and then you will be able to stake/unstake yourself

My address for testing: 0x182E1b58bc86582eE1f582aD5Aa5BDfAbAf5b495

[JCaraballo113]

@rzadp I have sent you some of our token for use in staking with @useDapp/core here is the tx receipt: https://goerli.etherscan.io/tx/0xb81a38639c9a36cb3b6f1208398d205e1327caadb7db5fa69d9fcb639a903bec

[rzadp]

@JCaraballo113 OK, what about the address of the contract for staking and its ABI?

[JCaraballo113]

@rzadp here is the contract address for staking, it's verified so should have everything you need? https://goerli.etherscan.io/address/0xBED33e388d6079A55E19FAD54C9668CF95631390

[rzadp]

@JCaraballo113 I tried to reproduce the issue, but it worked for me. Here are my steps:

0. increaseAllowance for my tokens on the contract
1. stake amount 1000000 using etherscan - tx
2. unstake amount 1000000 using etherscan - tx
3. stake amount 1000000 using useDApp - tx
4. unstake amount 1000000 using useDApp - tx

It all worked OK. My useDApp code snippets:

const CoveyStakingInterface = new utils.Interface(CoveyStakingabi)
const contractAddress = '0xBED33e388d6079A55E19FAD54C9668CF95631390'
const contract = new Contract(contractAddress, CoveyStakingInterface)

const stakeFn = useContractFunction(contract, 'stake')
const unstakeFn = useContractFunction(contract, 'unstake')

const handleStake = async () => {
  await stakeFn.send('1000000')
}

const handleUnstake = async () => {
  await unstakeFn.send('1000000')
}

What can be observed, is that useDApp by default estimates gas limit of a transaction with a very small margin (roughly 99% of estimation is consumed by the transaction). For larger buffers of safety, we added a gasLimitBufferPercentage configuration option. However, I did not use it, and my transaction were within limit and went through.

Estimation is done using ethers - perhaps there is a problem with the version of it? We're using version 5.6.9. @JCaraballo113 If you're using lower, can you try upgrading?

[JCaraballo113]

That's probably it. Will test and let you know

[JCaraballo113]

@rzadp this was the issue. Closing.