Questions tagged [erc-20-approve]
The erc-20-approve tag has no usage guidance.
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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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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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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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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 ...
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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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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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how to fix "ERC20: insufficient allowance" error? [duplicate]
I wrote a very simple contract to use the erc20 functions in another contract and the first thing I tried was transferFrom function, which works perfectly when I'm sending tokens from msg.sender(which ...
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"insuffiecient allowance" running my unit test
I'm developing in remix a lottery SC. I have a problem when I run buyTicket() function. On remix I fix it giving approve to SC address from erc20 function, but I don't know how to do it when I run my ...
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approve contract in wbnb
I deployed a contract on the bsc network to execute functions on the blockchain then I approved my contract at the wbnb address to make purchases and/or sales from the contract.
What am I allowing ...
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How IncreaseAllowance and DecreaseAllowance function solve mitgation problem?
I was going through openzeppline code for ERC20 Token and found that While working with approve function in IERC20 interface they describe mitigation problem : Link
I don't understand how ...
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Testing `approve` function
I would like to test a contract where I use the approve function of an ERC20 token.
Is there any test suite that allows doing that?
truffle? hardhat?
Any suggestion would be highly appreciated!
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Can Metamask be used for all ERC20 token?
How can I use WETH with Metamask wallet?
I can see ETH in my Metamask (Rinkeby TestNet, it works on Mainnet) but can not use other tokens.
Any Repository or lead will be appreciated.
If yes, What will ...
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ERC721 transferring NFTs and currency
I have a contract that I want to use as an NFT marketplace. It extends ERC721URIStorage
contract NftMarketplace is ERC721URIStorage ...
In on function I use _transfer() to move an NFT from the seller ...
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function selector was not recognized error
I'm extending OpenZeppelins ERC20 to create a Token that I use for testing in another smart contract. Here's how it looks:
//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;
import "@...
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transfer vs transferFrom "amount exceeds allowance" when sender is the same as msg.sender
I know the reasons for using transfer vs transferFrom but made the mistake of using the second one whilst doing some testing and I got the error "ERC20: transfer amount exceeds allowance". ...
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How to buy NFTs from my smart contract with custom ERC20 token? [duplicate]
i want to launch a NFT genesis collection for all the holders of the previous collection.
The previous collection gave the holders a ERC20 Token airdropped. So the holders have the custom ERC20 Token.
...
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how to use function approve() and function transferfrom() in a dapp?
hello
Me and my team are working on a staking/subscribing dApp on the ethereum blockchain using erc20 stablecoins like usdt and dai. We encounterd an error on the approve() and transferfrom() ...
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Unable to get ERC20 token approval to accept BUSD
I've tried almost every tutorial and help available online trying to accept BUSD or any ERC20 token in my solidity smart contract. I'm deploying the contract on Binance Testnet and I have 20 BUSD in ...
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Is this the correct way to handle a approval for ERC20
Please let me know if this is correct.
function handleApproval(IERC20 _token, uint256 _numTokens) public returns(bool){
_token.approve(address(this), _numTokens);
return(true);
}
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Differenciate logs entry Approval between ERC20 and ERC721
For a dapp, I'm currently focused on the Approval event to track and list the tokens approvals for a given address.
ERC20 and ERC721 are quite similar. They offer Approval events :
ERC20 : Approval(...
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ERC 20 Royalty implementation
Hello Guys i want to implement a royalty fee on whenever my custom ERC20 token gets transfer between accounts any idea to implement this or any tutorial pls any help would be appreciated
function ...
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Reverted with reason string 'ERC20: insufficient allowance'
I'm newbie on solidity and I'm trying a simple ERC20 on hardhat with task for understand use case
I follow this steps
Mint in owner
Owner owns N token
Owner would to approve Receiver for receive ...
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How to call ".approve()" function of a token which ABI I don't have? In web3.js/ethers
I need to call .approve() function of a token which I address I know but which ABI I don't have. How to do it? Will it be enough to create ABI string which will contain the signature of .approve() ...
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How do you approve + transfer ERC20 tokens in 1 transaction?
I want to approve my tokens to allow a smart contract to transfer them for me to another contract.
Steps:
I approve my tokens for Contract A to spend on my behalf.
Contract A transfers my tokens to ...
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Is "approve" required only for transferring tokens? Not a native coin?
Speaking of Ethereum blockchain, or any other one compatible with it: Polygon, Avalanche and others: is calling the function approve(...) mandatory only, and only, when there's a token involved in ...
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Difference between Approve() and IncreaseAllowance() in ERC20 contract
Over the last few days, I have been looking up the best and clear explanation of the differences between Approve() and increaseAllowance() of the ERC20 contract. Still, I couldn't come up with a ...
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web3.py - How to get status from ERC20 approve?
I have a web3.py script that approves ERC20 tokens to maximum - Web3.toWei((2**256)-1,'wei') - to bunch of different ER20 tokens (some have 18 decimals, some have 6) on Fantom chain.
When i try to ...
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What does web3's approve do before a token sell?
I'm trying to implement a bot with python and web3 from some code examples.
All of them call the approve function before selling a token? What is this function for and is it necessary?
Thanks
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Can I bypass the "approval" mechanism for tokens within my own ecosystem?
Let's say I have my own ERC20 token FOO.
I'd like my users to be able to send their FOO to my smart contract FooSwap.
Is it acceptable practice to bypass the approval mechanism in the ERC20 Foo ...
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delegatecall approve of an ERC20 contract
I try to call approve from a contract of another ERC20 contract:
The delegate call:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract Delegate {
address public constant f24 = ...
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Why is there no approve function for MATIC token contract?
MATIC token is advertised as an ERC20 token. So why is there no approve function for MATIC token contract? https://polygonscan.com/address/0x0000000000000000000000000000000000001010#code
What is the ...
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Ethers.js - Error: invalid BigNumber string
I am trying to approve a larger amount of erc-20 tokens (it has 18 decimals).
await token.connect(signer).approve(contractAddress, BigNumber.from((1000*(tenToPowerOf18Digits)).toString())) :
If I try ...
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Approve many tokens with one transaction
I need the users to approve the ERC-721 token before the smart contract and transfer it to someone. the default "approve" function works fine. but I'm wondering how to approve many tokens at ...
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Can a smart contract approve a pending transaction on a multisig wallet?
Suppose I have a multisig wallet like a Gnosis Safe, which requires (say) two or three signers to approve any given transaction. In other words, the multisig wallet has its own wallet address, and 2 ...
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IWETH9 withdraw function - where is this function sending the ether to?
I've written the following function which swaps DAI back to WETH and then withdraws the WETH and returns the Ether.
After running the function on REMIX I've got the Ether on the contract balance as I ...
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Contract reverts when making calls to erc20 token contract from my contract
i have this basic contract that should work, but it keeps reverting because of the approve call in the constructor, i also notice transferFrom calls from my contract also fails after manually ...
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Fail with error 'TransferHelper: TRANSFER_FROM_FAILED' even approved in contract
I'm rying to swap some BNB -> Token, then swap it back, all in one solidity function. Here's my code:
interface IERC20 {
function approve(address spender, uint256 value) external returns (bool);...
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ethers.js - approve function returns "Error: cannot estimate gas"
I tried to create an ERC-20 token on the Ropsten testnet and then tried to call the approve() function but it returns this error:
Error: cannot estimate gas; transaction may fail or may require ...
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Do I need to use the approve function to transfer erc20 tokens from one address to another?
I'm making an nft marketplace and I want the buyers to buy the nfts with WETH.
function createMarketSale(address nftContract, uint256 itemId)
public
nonReentrant
{
...
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Estimated Gas in JS Doesn't Match Metamask Gas Fee
I need help with figuring out the estimated gas for an approval. I'm able to get a number but it doesn't match what's in metamask. I'm a noob to web3 and so I'm not even sure I'm passing the correct ...
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In airdrop contract, I want each registered user to claim free airdrop tokens
I'm writing a simple airdrop contract in which user will register himself using register(), and his address will be added to an array registered[].
After the registration period is over, admin (who ...
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ERC-20 Token Approval Failure
recently I made a swap from ETH to WETH and immediately after that tried to grant another contract approval to spend my WETH. The TX immediately failed after it was created and was never submitted. ...
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Send ERC20 Tokens directly to contract address to trigger to function in contract
We are trying to bypass allow method and make the contract more UX friendly. And instead of first allowing contract to spend and after calling transferFrom method, we are thinking about just sending ...
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Solidity: Error from function transferFrom even after approval [ERC20] [duplicate]
I'm new to Solidity. My contract tries to receive the Chainlink ERC20 token on Rinkeby testnet from a users address.
First transaction: user gives approval. This goes through.
Second transaction: user ...
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Approve ERC20 token inside a contract function
I would like to understand why, approving an ERC20 token inside a contract function doesn't work.
Suppose that I create a function in my contract, that calls an approve for an ERC20 token for the ...
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Be notified when an Ethereum event occurs
I recently asked another question, but I deleted that one because I can narrow down my question to something simpler.
Suppose an ethereum ERC-20 token contract can emit the following event:
event ...
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Transferfrom and approve not working
I have erc20 tokens. Now I want to send these tokens to the current contract. How can I send it?
function bid(uint256 tokens) public {
require(block.timestamp < time,"time exceeded"); ...
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ERC20 Token Transfer Issue
I have a test token (ERC20) deployd on ETH test network (Kovan)
The token was deployed using Unicrypt tool
So far everything ok, but the issues is how can i transfer tokens from an outside smart ...
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How can I send my NFT (ERC721) Token (minted on ContractA) to another Smartcontract (ContractB) so that it is allowed to transfer it?
I try to send my NFT token#300, which is an ERC721 token, minted on ContractA, to antoher ContractB, so that ContractB is now the owner of this Token#300 - so that the ContractB is now allowed to ...
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Accept tokens in Smart Contract without allowance [duplicate]
I'm trying to develop an Smart Contract function that accepts and ERC20 token, and send it to another address.
I know that I make the user to call approve and later execute the function:
//check SC's ...
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