Questions tagged [erc-20-approve]
The erc-20-approve tag has no usage guidance.
136
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Getting error ERC20: insufficient allowance even after the user approving the tokens. Need help with debugging
The following code is from a Stablecoin project.
To gain more context, please refer to this Github repo.
I've added a new function to the DSCEngine.sol name collapseDsc() which is responsible for ...
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1
answer
18
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Can approve function be malicious?
I'm so confused on how approve functions works:
If myToken contract has an approve function but the owner did not approve the contract B. Then contract B deploys a function and create a function that ...
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1
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34
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Invalid Permit Signature - Same Signature Generated by Different Address?
Our dApp uses Permit for gasless token approvals. We are generating a signature request with signTypedData, and it works except for a few strange occurrences where I am getting back an invalid ...
2
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1
answer
29
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Transfer tokens to and from smart contract [closed]
I would like to have a new ERC20 token and one or two smart contracts to do automatic trade with specific cryptos.
Example: I can buy 1 token from the contract in exchange for 1 USDT.
I can sell a ...
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1
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24
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Execute ERC20 Approve outside of ERC20 contract
I am rewriting the solidty-by-example.org crowdfunding exercise.
IERC20 public immutable token;
function pledge(uint _id, uint _amount) external {
Campaign storage campaign = campaigns[_id];
...
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26
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How to check approvals for bunch of addresses
I have a list of ethereum addresses and I need to check which contracts and which approvals for a particular token they gave. I only need query approvals for one specific token. is there some ...
0
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1
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28
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ERC20 approval confusion
I have a smart contract which looks like this.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/...
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20
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Fantom cannot approve spending USDC token
I am doing simple approve operation on USDC token in Fantom network.
Here is my payload:
functionParams {
from: '0xd775b00b5cf6e954aed8408202367a1bae6ac55f',
to: '...
1
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2
answers
56
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Implementing an ERC20 Smart-Contract within another Smart-Contract
I’m trying to create a contract that lets people choose to pay for their transactions with either ETH, or another ERC20 Token - one that I’m creating and for now calling “DummyCoin”.
So basically when ...
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1
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91
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Metamask - get value entered from calling ERC20 "approve()" method
When we're asking a user to approve() the spending of a proprietary ERC20 Token for the first time (like say DAI, or SUSHI, etc.), the user has to enter the amount they're willing to approve - like ...
- 959
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23
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I am trying to create a contract to stake ERC20 token and getting this error "ERC20: insufficient allowance". I used approveContract to approve
I first approve allowance through 'approveContract' function and then try to transfer the amount using 'transferFrom' function of ERC20. But getting error :ERC20: insufficient allowance:
function ...
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1
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44
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insufficient allowance Error .. ERC20
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import &...
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0
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1
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38
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Token allowance of router address
Pretty much every coin with taxes has an allowance function to give the router allowance over max uint to be able to sell the tokens.
However, I always see the allowance given to 'router', which ...
- 185
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1
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40
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transferFrom not working. Estimate gas fee error. Cant find the bug
Code of contract followed by an explanation and requirements. Everything works but trade function.
/**
*Submitted for verification at Etherscan.io on 2023-05-16
*/
// SPDX-License-Identifier: ...
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1
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2k
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How can I remove custom spending cap on Metamask?
When I call the approve function of the ERC20 token standard, it asks me to set a custom spending cap, as shown below.
But I need to use the default value every time without clicking "use ...
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148
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Can I cut a fee using multicall on Uniswap V3?
I developed my own frontend for Uniswap V3, and I was asking myself if I could cut a small fee of the input token using multicall.
Basically, I would calculate what 2 percent of the input token would ...
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20
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Why my ERC20 approval function has the same owner and spender?
Why my ERC20 approval function has the same owner and spender?
//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/...
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1
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199
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Getting Fail with error 'ERC20: insufficient allowance'
First I'm deploying Cafe contract and get deployedId from it and then deploy CAFToken contract with deployedId of cafe contract. I've also added deploy script and test case, I guess everything is ...
0
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1
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167
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ERC20 increaseAllowance exploit?
I have my own smart contract. Users on my webpage needs to first approve (increaseAllowance) and then they call "donate" function and part of the assets are sent to my vault and the other ...
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3
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2
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475
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ERC-20 token approval fails if amount is close to maximum balance
So I am using Wagmi, which uses Ethers.js under the hood. I have to approve the router address first in order to buy the other token.
It works when I use the exact or slightly greater amount than what ...
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1
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1
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124
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TranferFrom in delegate call
I have an ERC20 test contract, also I did multicall with delegatecall function instead of call.
I have a three accounts: account1, account2, and account3.
account1 can spend tokens from account2 (I ...
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2
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0
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82
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Use Brownie to send ERC20 tokens to a payable function with the amount of tokens as an argument to the function
I have the following AlgoToken contract:
interface StableCoin {
function balanceOf(address account) external view returns (uint256);
function allowance(address owner, address spender) external ...
1
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1
answer
595
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ERC20 Tax on sell (via swap)
I'm struggling with taxing upon swapping a token back for ETH. I can't figure out what I'm doing wrong here. I'm using Hardhat testnet forking Goerli to work with the Uniswap contracts. Also made ...
2
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1
answer
28
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Manage tokens on the behalf of to call a smart contract
I would like to transfer tokens to defi smart contracts on the behalf of a third-party.
I see no option apart from (1) the third-party to transfer to me directly (2) the third-party to pre-sign ...
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2
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715
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Failing to trying to approve contract using ethers.js (CALL_EXCEPTION or cannot estimate gas)
I am having trouble calling a simple ERC-20 approve function from the front end on the Arbitrum network. Any insight is greatly appreciated. I will outline my code below.
I am retrieving the provider ...
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0
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225
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estimateGas with prerequisites (gas estimation requires approvals first)
I am trying to estimateGas for an Ethereum transaction with ethers signer.estimateGas(). This transaction should execute several trades on arbitrary DEXs.
To execute the transaction approvals of ERC-...
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0
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16
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Verifying signed messages
I sent signed messages to claim ownership of various tokens yesterday. I'm wondering how long to get them verified as I couldn't do it via the source contracts.
2
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1
answer
2k
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"gas estimation failed" error using Uniswap. Can't fix it, please help
I can't sell alt-tokens back into ETH. This is an issue with multiple tokens, not just one and they all have very high liquidity ($Kabosu and $OHMI).
I immediately get the error 'gas estimation failed'...
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2
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39
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Approve and disapprove a transaction
i want to develop a contract student in which student sign a transaction to update its record and owner would be able to approve or disapprove this transaction how would I able to do this.
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253
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Token approval questions and issues
I had a DEX approve 1000 USDT. I then traded 1000 USDT. The next day I want to trade another 1000 USDT from the same address, but the same DEX asks me for approval again! On Etherscan Token Approvals ...
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1
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21
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What happened to these tokens?
I send some Matic token in one of my wallets to the other for cover fee of a transaction (0.05)matic
but as soon as transfer succeeded, this amount transferred to another address, without any approval ...
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138
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Uncertain how to correctly implement Approve and TransferFrom for ERC20, could you kindly help me to understand?
Having trouble understanding how to correctly implement Approve and transferFrom. Some guidance would be much appreciated, thank you for your time. Below is my Deposit function:
/ Users can deposit ...
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1
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52
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move approved ERC20 to another contract
I created a contract that acts as my entry contract and gets an address for my second contract that would then call UniSwap exactInputSingle(). for the token that I'm sending to the first contract, I ...
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4
answers
507
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Allowing contract to take ERC20 tokens from msg.sender
I'm kind of new to Solidity and struggling with allowances and approvals. I want my smart contract to be allowed to take ERC20 tokens (LINK in this case) from the msg.sender. I'm using Remix on Goerli,...
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236
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How do i revoke an ERC20 or ERC721 token approval given to a smart contract
I've granted allowance to a smart contract to spend some tokens on my behalf, but it seems i gave it unlimited access.
I want to revoke this access as i now know that this could be a potential opening ...
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31
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I am using safe-connect to make swaps between a wallet, i am not able to find how to approve for example in Pancake to enable cake
The implementation is based on this repository which is great: https://github.com/tschubotz/safe-connect/blob/main/src/App.tsx
I am able to handle swap transactions, but i cant seem to find a way to ...
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2
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193
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How to set approval for all my erc 20 token on my marketplace smart contract
I am trying to build an nft marketplace where users buy nft using my own erc20 tokens. I want to eliminate the need for the user to set approval for the marketplace smart contract before they want to ...
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36
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How can I access current time inside transfer function in ERC20 contract?
I want to create a ERC20 contract in which inside the transfer() function I would check if the msg.sender can transfer tokens. This check will be like those we have in stock markets where when someone ...
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1
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49
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Can a user transfer X and Y tokens to a smart contract in a single transaction/interaction with the smart contract?
I'm trying to develop a contract to which users would send certain amounts of tokens A and B to the smart contract. Easiest/obvious way to do it would be to do several transactions in this order:
...
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1
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337
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Problem with setApprovalForAll( )
I was just scrutinizing the source code of an NFT marketplace. within the createNFT( ) function of their smart contract, I witnessed there is a setApprovalForAll(_marketplaceAddress) right after the ...
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370
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When address A approves a contract S to spend X ERC20 tokens from it, can anyone invoke that spend, or just address A?
Assuming standard flow of events
User, who is owner of address A approves to spend X ERC20 tokens, using approve method to a smart-contract S from address A.
Then, user calls S to spend that amount X ...
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1
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153
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Uniswap's swapExactTokensForTokensSupportingFeeOnTransferTokens gives "transfer amount exceeds allowance" error
I am experimenting with Uniswap's swapExactTokensForTokensSupportingFeeOnTransferTokens method by attempting to swap USDC -> WETH -> UNI-v2 using ethers.js just for the sake of understanding ...
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2
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46
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What happens if `transferFrom` fails after `approve` (Risk of remaining allowance)
I'm trying to call Uniswap V2 addLiquidity function, which calls transferFrom internally, and therefore approve must be called beforehand.
I would like to do it from a TypeScript code. In that case, ...
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141
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I am unable to transfer an ERC721 token that is owned by the wallet calling the function to the contract address the function belongs to
This is the start of a contract i'm writing, to enable two parties to trade ERC721 tokens via an escrow service.
The first step in the contract is that the trade initiator will deposit a token to the ...
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2
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142
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Is it possible to have another wallet execute a transaction on your behalf?
Is it possible to sign a message/transaction, then have another wallet execute the signed message/transaction without first calling "Approve"?
This question is for both ERC20 and ETH.
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14
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Why we give crazy amount of approval to DEXs?
I just discovered that we give a crazy amount of approval to DEXs when we approve to swap tokens. What is that?
Doesn't that mean their contract can take all the balance? The contract probably doesn'...
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1
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374
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How to run the approve method of Matic smart contract on Mumbai Chain?
I am trying to interact with Matic smart contract on Mumbai chain. The contract address would be - 0x0000000000000000000000000000000000001010.
This code below is calling the approve method.
...
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2
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258
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giving contract permission to spend eth
Since eth does not have a contract address, how does one allow a contract to spend it. For example - I put in a swap request - 10 eth for its amount in usdt for example - could the contract spend my ...
user106332
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767
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Staking and ERC20 Approve (RPC Error: execution reverted: ERC20: transfer amount exceeds allowance)
I apologize if this question might seem a bit simple beforehand. I'm trying call the deposit function from my frontend, but it gives me the error mentioned above. I am confused as to if this is a ...
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156
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Approve and Transfer ERC20 Tokens in contract
I'm pretty new to solidity and struggling with some pretty simple stuff so I was hoping somebody would be able to help me out. Basically, I want to be able to send an existing ERC20 token (ie: USDT) ...
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