Questions tagged [blockchain]
The Ethereum blockchain is a distributed database based on the Ethereum whitepaper specification and stores both the full transaction list and the most recent state.
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web3 (then property) in ethereum node
Would you please help: When I run the below command in my nodejs console I get the below error: (I am using web3 0.20.0) on Windows 10
web3.eth.getAccounts().then(list => {accts = list})
...
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I want to retieve data from contract A that has been already stored in the contract B by contract A?
dex.sol(contract A)
//SPDX-License-Identifier: MIT
pragma solidity 0.8.19;
import "./storage.sol";
contract dex1{
storage_contract public contractaddress;
constructor(address ...
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How to make payment gateway and confirm from transaction hash
I am looking for a payment solution for my website using crypto. I have seen some websites that display a modal with a QR code and a recipient address. I wonder how they know if someone has deposited ...
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Smart Contract - Update implementation using a Relay with delegateCall
I know that smart contracts are supposed to be immutable and that's the whole point, but to expect someone to implement a logic that never changes (no upgrade or no bugs) from day 1 is also ...
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"Undefined" error when i type "todoList = await TodoList.deployed()" in truffle console
I was trying this Beginner tutorial on smart contracts and solidity. I typed truffle compile, truffle migrate and they ran without any error . when i opened truffle console and typed TodoList = await ...
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What are the Ethereum disk space needs?
How fast is Ethereum blockchain growing and how big is it likely to get in the future? Is it still about 1 GB per month? Are there any data pruning or compression algorithms in place or planned to be ...
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Ethereum Blockchain Size
I synchnorized Ethereum blockchain in my AWS Ubuntu 16.04 server with 110GB Hard Disk.
The command I used is geth --syncmode=fast --cache=1024
According to bitinfocharts, the total size of Ethereum ...
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Find Current Blockchain Size?
How can I find the current blockchain size? (Obviously, I mean without downloading and installing a client, downloading the blockchain, and measuring on disk.)
I would also like a way to determine ...
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Solidity: Is there a way to get the timestamp of a transaction that executed?
Is there a way for a contract to be able to get the exact time someone called a function in it?
For example, if someone sends funds to the contract address, is there a timestamp recorded by the ...
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We were not able to estimate gas contract solidity in testnet working, but in mainnet not work
We were not able to estimate gas. There might be an error in the contract and this transaction may fail.
function minterMint(
address to,
uint256 quantity,
address payee,
uint256 price
) external ...
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How to solve Unhandled Rejection (Error): invalid address error?
I am new to blockchain, I am getting this error when I try to login to the donor page.
Unhandled Rejection (Error): invalid address (argument="address", value="...
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How to connect peers which are on different computers in geth on private network?
I am trying to setup a private network and trying to connect peers. Currently I'm trying it on my laptop and virtual machine(VM) runing on the same laptop (both of them are connected to internet).
I ...
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After registry of both the consumer and prosumer properly, when I try to do the transaction, the transaction is reverted
//SPDX-License-Identifier:GPL-3.0
pragma solidity 0.8.13;
contract trade{
constructor() { owner = msg. sender; }
address owner;
modifier onlyOwner {
require(msg.sender == ...
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why does it matter to sync nodes with time?
As we know, time gets set on a block's header as the miner's current local time. Each node while accepting a block, checks if the new block's time is more than parent 's time and is not also in the ...
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Code:const web3 = new Web3(window.web3.currentProvider) Error: window.web3 is undefined
I am going to connect my contract with the website.However,there was something wrong with the web3? I'm not sure.
import Web3 from "web3";
const web3 = new Web3(window.web3.currentProvider);
const ...
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Degree verification process using blockchain
This question is specifically related to blockchain use case. I want to implement degree verification process using blockchain . I just need to know whether I am approaching my objective in a right ...
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How to get and decode logs of all transactions of a block in web3?
How to get and decode logs of all transactions of a block in web3?
My question is very similar to:
Is there a way to get the logs for all transactions in a block?
But the suggestions were given using ...
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Where does geth store data except for the AppData\Roaming\Ethereum folder?
The AppData\Roaming\Ethereum folder on my computer weighs 5GB, but geth has reduced my disk space by a lot more than 5GB.
Where else does it store data?
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Where to store IPFS hash other than infura.io without paying
I used infura.io to store IPFS hash few months ago in my Ethereum dapp based on React JS but now it's not free anymore and it is asking for my bank account details. I want to use it for small personal ...
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How can verify an NFT that I want to act as an access card?
Hey guys I'm trying to create a social group that has real world and cyber space meet ups.
I wanted the group to each have an edition of a NFT that I create and they get. When at these events how ...
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miner.start(1) triggers but not starting the mining
I am creating my own private ethereum blockchain.
sudo geth --rpcapi eth,web3,personal --rpc --networkid=15
Above command gives the below logs.
INFO [09-18|10:16:42.151] Maximum peer count ...
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How ERC20 Token balance are recovered during Ethereum chain rolling-back
My Answer:
Ok, the problem is really with Ganache ... If I use geth, everything is alright.
... ... sorry for your time ...
---------------- The Original Question --------------------
My ...
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Error HH8: There's one or more errors in your config file: * Invalid account: #0 for network: sepolia - Expected string, received undefined
I have this code in .env
API_URL = "https://eth-sepolia.g.alchemy.com/v2/<API>"
PRIVATE_KEY = "6**********2a4********************7b96***********5af*****1"
But when I run ...
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ParserError: Expected '(' but got identifier --> dao.sol:98:10: | 98 | function correctMap(uint256 _mapId) external { |
pragma solidity ^0.8.0;
contract EvacDAO {
struct EvacuationMap {
address submitter;
string mapData;
bool isValid;
}
mapping(uint256 => EvacuationMap) public ...
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could not be able to change my setmessage because (Transaction has been reverted by the EVM:
I am working on react. As I have deployed my contract onto a specific address which have a following code:
pragma solidity ^0.4.17;
contract Lottery{
address public manager;
address[] ...
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How to validate a transaction from any block in Blockchain
Given that we have a Blockchain with smart contracts. We have end users operating the platform for some time. Now one user wants to verify the claim of a transaction.
Example, I have to prove that ...
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Is it possible to re-route the “burned” gas from EIP-1559 and instead of burning it
Is it possible to re-route the “burned” gas from EIP-1559 and instead of burning it, send it to a smart contract
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How can I perform a pre-check transaction to verify if it will be successful without recording it on the blockchain?
We aim to implement transaction checking, specifically for swaps, to ensure they won't be reverted. This will help users avoid unnecessary gas costs.
I want to do this on the front-end, using the ...
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Is it worth to pursue master's on blockchain technology in USA? [closed]
Completed my bachelor's in computer science looking forward to do master's. Is it worth to take blockchain technology as my course, as I am really interested in crypto
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Why am I getting Error: missing argument: in Contract constructor (count=0, expectedCount=1,... and whats the solution
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "...
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Address as name of an array in solidity?
How to make an array with its name as address of user?
For example string[] public 0x7v77wfr349C9864De0119E94c3f8d.
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ProviderError: Error: Transaction reverted: function selector was not recognized and there's no fallback function
I'm trying to call a function[propose] from Openzeppelin governor.sol. The function is like this...
function propose(
address[] memory targets,
uint256[] memory values,
bytes[] ...
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Contract's transaction count in a certain period
I want to determine the number of transactions of a contract in a certain period. My question is that in the transaction receipt, if we want to say that contract A has x number of transactions will ...
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Stablecoin Development
Can anyone link me with some information on how to develop stablecoins that are fiat backed, I can't seem to find anything on this topic.
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How to call a payable function in ethers, which takes 0 input and payable bnb?
I have wrote it like this but it is always throwing error that inputAmount is not in range but it is in range,
const transaction = await preSaleContract.buyTokens({value: inputAmount,
from: ...
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failed connecting with virtual machine
I have 4 geth Nodes runnning on my PC
bootnode address is 192.168.1.2
the 5th node is running on Virtual machine with address ( 192.168.1.5 )
when i try to run the 5th node it doesn't sync with the ...
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How only allow NFT minting after course completion
I am new to ethereum I building a course page where you would get an NFT if you complete the course. Any idea on how to implement it.
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Creating geth nodes in virtual machines
I have 2 nodes
the first node is on my machine ( host ) with an address 192.168.1.4
the second node is on Virtual machine with an address 192.168.1.8
the ping working fine, but when I used this ...
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I got an Error in Encrypting the Private Key using ethers
const ethers = require ("ethers")
const fs = require ("fs-extra")
require ("dotenv").config()
async function main () {
const wallet = new ethers.Wallet(process.env....
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How to decode the event logs in polygonscan mumbai?
This is my transaction hash: https://mumbai.polygonscan.com/tx/0x79ed502a8d319ab3b278781042898115d9d6bece15d3d91626a7a6a39c0873b3#eventlog The event logs of the event DataCredentialized is not human ...
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List failed (ERC20-)Transactions for a specific address?
is there a way to show all failed (or all including failed) transactions regarding a destination address?
Example:
https://etherscan.io/tx/...
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Deploying a smart contract using DApp
I am new to the development of DApps on ethereum blockchain. I want to make a contract Management System in which users can generate their own tokens and crowdsale using my web application. I am able ...
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html:82 Uncaught ReferenceError: App is not defined at HTMLButtonElement.onclick (html:82)
It's showing me uncaught reference error in my index.html file
<div id="candidate-box"></div>
<button class="btn btn-primary" onclick="App.vote()">Vote</button>
...
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What is 2^187 target in the Ethereum white paper wrt PoW in Bitcoin?
The paper says that
The precise condition is that the double-SHA256 hash of every block,
treated as a 256-bit number, must be less than a dynamically adjusted
target, which as of the time of ...
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i have problem installing truffle ,when i try npm truffle -v i get this error message
truffle : File C:\Users\hp\AppData\Roaming\npm\truffle.ps1 cannot be loaded. The file C:\Users\hp\AppData\Roaming\npm\truffle.ps1 is not digitally signed. You cannot run this script on the current ...
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Anyway to recover lost ether sent to unowned wallet?
I was sent a smart contract by a "friend" described as an MEV sandwich bot. But when I started up the bot and finally took a hard look at the code, I realized that all of the ether was ...
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How to run Chainlink Project using eth-brownie python
I had installed eth-brownie using command
pip install eth-brownie
after Brownie installed.I had bake existing Brownie project into a new directory.
mkdir MyChainlinkProject
cd MyChainlinkProject/
...
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web3.js not working with React JS
I have installed web3.js
npm install web3
my App.js
import React , {Component} from "react";
import web3 from "web3";
import detectEthereumProvider from '@metamask/detect-provider'...
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ethers.js version 6: TypeError: wallet.getTransactionCount is not a function
I am getting the following error using ethers.js version 6 while getting the total transaction counts.
TypeError: wallet.getTransactionCount is not a function
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Unhandled Runtime Error TypeError: Cannot read properties of undefined (reading 'args')
I get this error Unhandled Runtime Error
TypeError: Cannot read properties of undefined (reading 'args') whenever I want to create an nft on my decentralised application and it only appears after I ...
