All Questions

I have question My geth show me like that "Deep froze chain segment" repeatedly What mean??

I am producing a game for a hackaton community to expose more people to Ethereum and blockchain. After hacking something my hackers will get many different seed phrases (similar to one generated by ...

I use the command npx truffle unbox react to develop a dapp but I get these errors below in my console. Can anybody help me? I really don't know how can I solve them.

Since I've made stats from geth full node by calling rpc api, it is burdensome for me to stop geth a few hours. Nowadays my local machine uses about 95% disk, so I want to migrate my /chaindata to ...

I am unable to open a wallet I created roughly 2 years ago. In that time I have been using MEW, MetaMask and something that I installed locally on Window, which I forgot the name of. Not sure which ...

I try to send erc20 tokens in this way var Tx = require('ethereumjs-tx'); var Web3 = require('web3') var web3 = new Web3(new Web3.providers.HttpProvider('https://mainnet.infura.io/v3/...

Problem: All method calls to my deployed contract return null Versions: Geth: 1.9.9-unstable Git Commit: c2d65d34d5c6f27b8d1a52280964023a3eefd66e solc: Version: 0.5.13+commit.5b0b510c....

I'm able to listen to contract events on desktop but it's not listening on mobile (coinbase wallet). const contractInstance = new web3.eth.Contract(abi, contractAddress); contractInstance.events....

Ubuntu 18.04. Truffle v5.1.2 (core: 5.1.2) Solidity v0.5.12 (solc-js) Node v13.2.0 Web3.js v1.2.2 When I execute truffle unbox pet-shop on terminal, I get error ✔ Preparing to download ⠼ ...

Is it possible two different wallets (address) make the same signature for one message? I have one message: '...

I'm new to solidity and wondering where the emit should stay inside a function. For example: function getPlayers(address players, bool enabled) external { require( msg.sender == _admin, ...

I want to run my own eth fork from mainnet (keeping history of transactions, balances & etc). How can I start my new geth instance that will start working after ###### block of mainnet chain? I ...

I still do not get the concept of Ethereum. How does the ETH money/coin/value is generated? Who generate that? Are the miners who process a transaction get ETH from the other user (fee) or the system ...

I have a question in my think about shuffling policy. I would appreciate it if you tell me about any contradictions (can’t be justified) or supplement. Suffling shard is high cost in node because ...

There is an exchanger, during registration, unique eth addresses are created for each user, I store private keys on the server, how to make sure that if users deposit erc20 tokens to their addresses, ...

I wanted to build go-ethereum source code in my local side and test it in geth. I have followed up the instructions in the github go-ethereum as it is. However, I have got fail with some errors when I ...

I have this tests that supposedly pass (in the terminal, I can see the checks). But they never actually run the code: it("should add an exam to the exams list", () => { let hash_test = "...

When I try to interact with the contract with web3.py, I am using ganache, I get the completely useless error message: ValueError: {'message': 'execution error: revert', 'code': -32000, ... , '...

I created a vesting contract it is same with maticvestingcontract https://etherscan.io/address/0xcbfe11b78c2e6cb25c6eda2c6ff46cd4755c8fca#code when what should ı do for withdraw from vesting contract. ...

I was trying with a simple contract,when I do "node compile.js" in my windows cmd it throws an error.I was using vscode it showing error in const solc = require('solc'),I installed everything ...

Do you guys know an easy Discovery Protocol implementation that is not deprecated and is powerful enough. I've checked some, but all of them are not suitable for my task (reasons below). Checked ...

file web3.js import Web3 from 'web3'; const web3 = new Web3(window.web3.currentProvider); export default web3; file image.js import web3 from './web3'; const address = '...

I try to recover a public key (not an address) from a message and a signature. I have the following message: def offer_hash(msg, nonce): types = ['bytes', 'bytes', '...

OS: Ubuntu 18.04 I am following this guide (https://www.codeooze.com/blockchain/ethereum-dev-environment-2019/) to install Ganache, npm, and then Truffle. Everything is fine till I execute sudo ...

I want to document my Dapp including the "data structure" (i.e. the relationship between different contracts). Is there a good way of modelling smart contracts that anyone has used successfully?

UPDATED: I am trying to download source code of open source verified contract from Etherscan.io. Here is my procedure as directed by Ann. 1. Download CSV file of captioned contracts. 2. Write ...

I would like to save daily prices of about 3000 items (about 2mb in size) on a public blockchain, and I would like to create a DAPP to retrieve the data. I am considering saving the data on Ethereum. ...

I've been playing with this over the past weekend and it seems impossible, I guess since it's considered a big security issue if it was possible. Example to illustrate what I am trying to achieve: ...

ethereum-wallet-xxx.jsonfile exists when purchasing genesis. I do not know if I set a password. Is this possible to restore? There are encseed, bkp, ethaddr, btcaddr, and email file formats.

I am requesting test ether from a Ropsten faucet, but it is showing an error. Please help me to resolve this error.

I am trying to understand Chainlink, and I am running into a wall. I found this tutorial, which explains how I can create a job spec using JSON. The tutorial explains that you can specify the url, ...

Python code: from web3 import Web3 import json web = "http://10.0.141.114:8545" web3 = Web3(Web3.HTTPProvider(web)) abi=json.loads('[ { "constant": false, "inputs": [ { "name": "_cad_number", "type":...

Expected identifier but got 'function' function test() public{ ^------^

I have deployed my contract locally into Ganache (GUI) and then send/call lot of transactions. After these transactions, now I want to check the current status of all state variables. Is there any way/...

I am using geth to sync up with the Rinkeby testnet using the command: geth --rinkeby --syncmode "fast". First it downloaded the blocks, then account states, and now new chain segments are being ...

How can I accomplish something like this: accept ether, set owner or anything and then return 1, throw...just return This doesn't seem to work despite crossing through functions and using if ...

I'm getting the error below when trying to call a function in my smart contract to transfer a token from the current wallet in MEW to an address. Here's the screenshot, https://nimb.ws/NZCD8u I used ...

What kind of node synchronization should I choose to work with a centralized exchange? Is there enough quick synchronization, or is full synchronization necessary?

Given the following example: function x(address receiver) public { receiver.call.value(msg.value)(); } Am I correct that receiver can be any address but msg.value cannot be controlled via ...

Im doing the tutorial at https://github.com/ConsenSys-Academy/proof-of-existence-exercise and running into the following error: $ truffle console truffle(development)> var poe = await ...

I want to query kinds of ERC20Token which some address holding,I used etherscan's api but only find ERC20Token's balance. Is there one api can finding?

I am making my project of BlockChain subject. I am having a problem with deploying smart contracts. Can anyone help me with this error I have tried everything I could but still failed to resolve this ...

I have been studying block chain for a while, and I came to know that decentralisation of data is its greatest pros. From my understanding, if block chain is massively adopted in the future, we will ...

I want to query all transfers regarding a contract with Nethereum. This means, in the end I want to have all transactions, so that I can print a statement of account. I suppose with the web3.js ...

I have a truffle project, if I migrate it onto ganache-cli and then interact with my contract (via Metamask) it works great. But if I try and do the exact same thing using ganahe-gui the contract ...

When I deploy my truffle smart contract on test networks like Ropsten and Kovan, can I interact with it using multiple PCs at once simultaneously? And will the data updated from one PC be visible on ...

The question is about the node, is the node functionality enough in fast synchronization for the functioning of a centralized exchange? Or is it necessary to download a node in full synchronization?

In other words: If contract B is called by contract A: B: function externalcall() public { //msg.sender is contract A... msg.sender.call.value(0); } Then assuming msg.sender.call above calls back ...

What server configuration is needed to raise a node? And will there be enough nodes in fast synchronization mode for the exchange, or is full synchronization necessary?

I have read about smart contracts and I am left with some doubts. Every invocation of a function in smart contract is a transaction which costs some ether.A miner chooses a smart contract on ...