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Questions tagged [erc-20]

The ERC20 Token Standard is a set of 8 functions to be included (in an agreed upon language) in a smart token contract in order to enable interoperability across multiple interfaces and dapps. These functions relate to (1) how tokens can be transferred (2) how to access data about the token, and (3) how to format key events like transfers and approvals. ERC stands for Ethereum Request for Comments.

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Unknown Selector Error (0x98296c54) in BIGTTokenTest.t.sol

Unknown Selector Error (0x98296c54) in BIGTTokenTest.t.sol Description: I'm encountering an "unknown selector 0x98296c54 for VmCalls" error in my testbobBalance function within the ...
8 votes
5 answers
13k views

invalid opcode: opcode 0x5f not defined

I'm new to Solidity and it's my first try to write a smart contract using Openzeppelin, Pancakeswap and BEP20 libraries basically to make a BEP-20 token. When i try to deploy the smart contract, i get ...
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0 answers
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Subdecimals in ERC20 tokens and wallets?

Is there any standard or any discussion of standard for wallets to display not the standard unit of a token, but perhaps 10^-3n, such as one thousandth, one millionth. Much like wei, gigawei, etc. ...
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1 answer
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Is there Uniswap V2/V3 function to get initial token supply amount in pool?

I need to get initial token supply when liquidity pool was created by querying Ethereum node (RPC) or Uniswap contract and not Mint() function, is it possible to do (python)? To get reserves on any ...
0 votes
1 answer
344 views

How to use web3 to send an ERC-20 token to a contract function

I know how to use web3 to send USDC tokens from one address to another, by using "web3.eth.Contract (ContractABI, ContractAddress) to create a Contract object, and then creating a data object ...
1 vote
1 answer
2k views

Uniswap fork: remove liquidity error

I am trying to fork uniswap. And I have a problem when liquidity is removed. Problem in UniswapERC20. I don't know what's wrong. Step by step (repeatedly for Rinkeby and Ropsten): Copy Uniswap ...
1 vote
1 answer
395 views

Old ERC-20 TRX Tokens Swap Issue

I tried the instructions given here to swap my old (pre-2018 swap) TRX tokens based on the Ethereum network to the MainNet ones. I sent the tokens to the smart contract address mentioned in the ...
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2 answers
2k views

How many tokens are transfered actually when we are using decimals

I have a code below and when I am transferring 1,695,000,000 to a particular address, so actually 0.000000001695 are being transferred. Why is it so? Does that mean to transfer 1.695 billion tokens I ...
0 votes
1 answer
776 views

Is it possible to burn tokens that are in a contracts balance?

As the title states, is it possible, to burn tokens that are in the balance of a contract? I made a mini game where the person who calls the external function, it suppose to burn the tokens in the ...
2 votes
3 answers
1k views

How to get test ERC20 tokens on mumbai testnet?

How I can get DAI, USDC, WETH, or any other erc20 token for mumbai testnet ? I am working on lending and borrowing platform so I need test tokens for that.
2 votes
2 answers
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To transfer tokens from owner address to an address, if latter address moves some other tokens to a given particular address

I am writing a contract for an ERC20 token (say ABC). Is it possible to airdrop some of these newly minted ABC tokens to those ERC20 addresses, every time, if they transfer a different token (named ...
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2 answers
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How to transfer ERC20 tokes from Blockchain wallet to MyEtherWallet?

I got some token and by mistake sent them to my Blockchain ETH address. Now, what is the process of transferring them to MEW? They talk about exporting your private key, what does that mean and to ...
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1 answer
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How can I get a list of token spending allowance for a wallet address?

Let's say I am an end-user who has been testing dapps here and there and I've approved multiple tokens spending for my wallet for different dapps. Is there an easy way for me to get the list of which ...
1 vote
1 answer
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ERC20 tokens in Metamask suddenly not showing

I've been using Metamask in Chrome for a while and had a list of ERC20 tokens in Ropsten network already added in the Assets section through their contract addresses: DAI address: ...
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2 answers
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How can I import an existing ERC20 token into my contract?

I'm trying to develop a staking contract. All of the guides I've seen utilize either payable (ETH) or a newly created token. How can I import an existing token (presumably via address) into my ...
1 vote
1 answer
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ERC-20 Tokens Stuck on MIST Multisig Contract on the Polygon Network

Help! I can't get access to these tokens.... I have ERC-20 tokens attached to a MIST multisig contract on the polygon network. Here's a contract similar to mine (by not mine). This might actually ...
0 votes
1 answer
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Congestion in ERC20, not allowing me access to my transfer unless I pay 10% or it will be lost

I transferred 3mil from Coinbase Wallet, CounbaseETF. I was informed that the transfer was congested in the ERC20 network and I will not have access unless I pay a 10% fee within 20 days. Is this ...
1 vote
1 answer
368 views

Cannot swapExactTokensForETH inside transfer of my token

I'm trying to create a token (calling it MyToken in this question) that on each transfer, it takes a fee from the transfer amount and does the following: calling the uniswap router to exchange this ...
0 votes
2 answers
4k views

USDT on Sepolia

I'm currently working on testing ERC-20 transactions on the Sepolia testnet and I'm looking to obtain some USDT for this purpose. Could anyone guide me on how to acquire USDT on Sepolia? I've been ...
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2 answers
455 views

ERC20 How to transfer the balance to a new address

I want to call the ERC20 contract with other contracts and transfer the corresponding balance to the contract caller. What should I do?
2 votes
1 answer
155 views

Are there any no-code tools for deploying ERC-20 tokens?

As the title says: are there any no-code tools for deploying ERC-20 tokens?
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1 answer
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Transferring funds after Permit is given

I have 20 ERC 20 tokens. I use Permit and give my signature to allow a contract to spend 20 of my tokens. However, I move these tokens to another wallet before transferFrom happens. What happens when ...
1 vote
3 answers
620 views

Can someone please help me understand address(this) in Uniswap liquidity

So I'm learning Solidity in creating a new token. I successfully created a token and implemented custom tax and burn functionalities. Now I'm trying to understand the Uniswap liquidity features. The ...
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2 answers
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Database column type (postgres) for storing erc20 token balances the correct way

I have an app that is pulling all erc20 tokens for each address. Now I want to store these values already calculated to the right amount into my postgres db. Right now, I am using the column type of ...
3 votes
1 answer
334 views

How to use enums for conditions on constructor?

I am learning to code with solidity. need help to solve this I have a membership system where users can have basic, gold, diamond membership types. Users can use coupons every 5 minutes and for basic ...
3 votes
2 answers
3k views

Constantly getting "Gas estimation failed" error when attempting to deploy ERC20 Token contract on Rinkeby testnet

I have included the code for the contract below. The error I get when attempting to deploy in remix via metamask is: Gas estimation errored with the following message (see below). The transaction ...
0 votes
1 answer
511 views

I need to know how to set a maximum buy limit per wallet

Yeah so I'm creating a eth token and I need to find a way that buyer have a purchasable maximum limit. Can anybody help me with that ? Can't find answer thanks a lot.
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1 answer
398 views

ERC20 amount exceeds allowance in tests solidity

I'm trying to transfer balance from one account to another, but whenever I try I get the following feedback... Error: Returned error: VM Exception while processing transaction: revert ERC20: transfer ...
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2 answers
497 views

How to retrieve the logs of transactions on one contract and multiple addresses

I have an application which should work as an exchange. Customers have their own Ethereum addresses on my Geth server, and they might receive ERC20 Tokens on them. I need to fetch the incoming ...
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0 answers
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How can i claim airdrop from contract with another wallet not whitelisted

i have an airdrop wallet to claim DOP token on erc20 which cant be transfer yet on chain, but the wallet is compromised, i need a way out
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1 answer
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Getting Error : ERC20: transfer amount exceeds allowance

contract Token is ERC20 { constructor() public ERC20('DonkeyCoin', 'DKC'){ _mint(msg.sender, uint(100 * 10 ** uint(decimals()))); } // now we can make the approve for the msg....
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I have a staked token in my wallet that seems to be increasing in amount over time. Is this a special type of contract?

I staked a token and the amount increases over time. Is this a special type of contract? Is it still considered an ERC-20?
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How do you actually link Real World Asset to newly issued tokens?

I've been exploring possibilities to tokenize real world assets, such as a real estate, and I came across the concept called Real World Asset Tokenization link. Aside from all the gibberish about how ...
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I have sent SYN tokens and are stuck in my ETH wallet. What can I do?

I have my SYN tokens stuck in my ETH wallet and can see them in etherscan. Anyway to send them out back to the original address the tokens weren't sent from? 0xF66Bd3fa316aBD9c44492bc92AefC90652AE9311 ...
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0 answers
18 views

Downscaling liquidity tax according to ETH reserves for fair distribution without presale

So I wanted to try and solve the problems that arise when releasing a token with very low liquidity. Presaling should absolutely be avoided since holders always dump at the start. Assume 50 to 100% of ...
0 votes
1 answer
376 views

How can i make a simple chartjs chart with ethereum contract address

i would like to have a chart on my site that prints the last price of a certain erc20 token i have seen a widget from ethplorer but i rather build my own chart but i cant find any documentation for ...
1 vote
1 answer
737 views

Want to Access remote dai smart contract in another smart contract

I want to transfer Dai tokens from account1 to account2. My account1 has 50 DAI tokens. Kovan Dai contract address given by makerdao is: 0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa. What I am doing ...
0 votes
2 answers
867 views

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 ...
2 votes
2 answers
4k views

How can I invoke an approve() function call from the user and not the contract?

I am working on a basic staking platform for practice. I understand that the user of the platform has to call the approve() function and pass the contract into it in order for the contract to use the ...
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1 answer
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TotalSupply of token not showing

Trying to practice web3, I want to show the total supply of ERC20 token by making a frontend. Please help ! import React, { useState, useEffect } from 'react'; import Web3 from 'web3'; import erc20ABI ...
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2 answers
389 views

Token Contract Verified and Signed on Mainnet Does Not Show MINT Function

The Token Contract Address https://etherscan.io/address/0xa2e7a0d1cfeda4d3977277265e205f6092d02e3b was successfully tested on Ropsten (See Ropsten Contract Address ...
0 votes
1 answer
357 views

There is an address that is hacked, the bot is monitoring it and payments are received regularly!

So, the bot instantly cancels these payments by sending, for example, 0.01 eth with a commission (fee) of 0.009 to another wallet, or even canceling everything through self - sending 0 to the same ...
0 votes
1 answer
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Gas Estimation Error - Simple Token + ICO Project

I am a beginner in Solidity and created a simple token + ico file and am testing the code on Base Sepolia Testnet and am running into a peculiar error. I keep getting Gas Esimation Error on the ...
0 votes
1 answer
38 views

SwapRouter02 not working with custom ERC20 token

I am trying to programmatically swap ETH for a custom ERC 20 token (let me take a meme token as an example) Here is my code that I swapped ETH for USDC: const { ethers } = require("hardhat");...
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0 answers
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Minimal proxy contract, can make pair but can’t add liquidity

I have a cloneFactory which produces ERC20 compliant clones based on a master template. I’m able to deploy my clones and even create pairs for the clones. But when I want to add liquidity (...
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0 answers
18 views

Smart Contract on Trust Wallet

After the lock up period of 180 days in a smart contract Ethereum blockchain how can I get my fund back? Should I do anything or it is received automatically?
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1 answer
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ERC-20 allowance always 0 after approval

I'm writing a smart contract that transfers ERC-20 tokens from wallet A (sender) to wallet B (receiver) and deducts a fee to wallet C (owner of the contract). The problem is that when I'm trying to ...
0 votes
2 answers
4k views

Transaction shows up on etherscan and metamask said it was sent, but my token balance is still the same

I made USDC transaction and metamask said it was sent and etherscan also say there was a transaction made as seen below. But my USDC balance is still the same as if it never left my account. And ...
0 votes
1 answer
375 views

Metamask not showing balance of custom ERC20 token (hardhat)

I'm trying to test a custom ERC-20 token using Metamask and Hardhat. After deploying my ERC-20 coin and minting some to one of the HardHat default accounts I try to add the token to Metamask. It is ...
1 vote
1 answer
98 views

Scanning for fresh wallets and deployer connections

My main goal is to listen for fresh wallets buying launches of a erc 20 token. We all know fresh wallets (funded from a central exchange) could be created by insiders or friends of developers. Or ...

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