All Questions

I have created a contract, wrote a migration and a test. When I run truffle test the contract is deployed locally and then the tests are run against it. All is working fine. I also added a function to ...

MISSION: Start a Geth node with a console while loading JavaScript function libraries at the same time I need to load function libraries at startup, without having to call loadScript() on the Geth ...

So, ERC20 tokens are bought depositing equivalent Price = amount to be bought*price of tokens) in eth to the smart contract eth address. So lets talk about BAT ERC20 token: If I am verified BAT ...

I have downloaded the ethereum source from https://github.com/ethereum/go-ethereum, is there anyway to build the source in windows 10 machine. As per the document it says use make geth , but it will ...

How can I work with USDT tokens from web3j? I have node from https://www.ethernodes.org/nodes

From what I gather, no... Simply an exchange that's named the same? https://serenity.exchange/

tl,dr: Remix shows a formatted transaction summary for transactions that are initiated within the Remix IDE. Is it possible to display the same output for an arbitrary transaction hash? Sorry if this ...

I'm trying to send Quantstamp (QSP) to Binance offline, using MyEtherWallet. In mew's offline helper... when I paste in the signed transaction (into the online MEW, as received by offline version of ...

Case This is a hypothetical question. Let us assume we own a group of stores, restaurants or cafes and want to give our customers the opportunity to pay per App, with our own system not an external ...

any one please help when show QR for receiving erc20 token can i enter amount like "ethereum:ethaddress?address=contractaddress&uint256=token" not working "ethereum:...

Smart contracts have great power to absorb money like a black hole. Almost 400$ Million is gone due to a bug in the smart contract of YAM. What was the bug that cause all the destruction? => Could ...

How do I deploy a contract on a test network using Remix 0.8.0 and MetaMask on a Firefox or Chrome browser?

I wrote a solidity contract using version 0.4.24 using OpenZeppline-solidity version 1.12.0. This used to deploy using the Nodejs version 8.12. The Nodejs version 8 is no longer being maintained from ...

We were trying to include oraclize query to get price feed in one our contracts, as of now we have observed that the first oraclize is free in kovan. Does same applies for mainnet or else we has to ...

I'm trying to subscribe to newBlockHeaders on the ropsten network, but it does not seem to work. The following code works for mainnet but not ropsten. Any ideas? const Web3 = require('web3') const ...

Interested to know if anybody has used this application in an offline setting.

I would like to have a button that switches between main net and ropsten on my app, in order to do so I need to programatically change the current network with MetaMask. But I cannot find aby ...

Truffle not deploy contract updates. truffle migrate compiles it but falsely say network up to date. OS: Windows Truffle v5.1.39 npm 6.14.5

I created a token in the Ropsten network. It wants abi.json when transferring with Web3. But the token I created did not give it. My token etherscan link https://ropsten.etherscan.io/address/...

I have more than one ETH wallet. I want to automatically combine these wallets into one wallet. For example, when I get an ETH in wallet 0x1, I want it to automatically transfer it to wallet 0x2. Can ...

Good evening. I registered on smatrix and I upgraded my first level 40hrs ago and my Eth was deducted. Yesterday, I checked my account ....then I saw 0payment sent but my 0.02 ethereum was deducted . ...

Been struggling in finding a way to estimate gas for calling a function. I was getting the error - Error: VM Exception while processing transaction: revert locally on ganache and getting Error: The ...

My transaction https://etherscan.io/tx/0xd4f9905b14e26ee96b243f47e734e1b7880dc2a23f8f847dae786fca0f3f9888 has failed and was marked as reverted 15 hours ago. Though i don't think my ETH wallet has ...

Heeey superstars thank you for taking the time to answer this question Me and my people are in the eth black smart contract but the site got offline is there anything we can do to get our money our ...

On every truffle migrate truffle deploy contracts even if they are not changed. although it doesn't re-compile Truffle v5.0.5

How can I prevent initializing Metamsk on window.ethereum.enable() or on creating a new instance of Web3?

For Ganache, there are several solutions. What about Buidler? They implemented their own local blockchain, buidlerevm, which is different to Ganache.

I have this simple code in remix.ethereum pragma solidity ^0.6.1; contract SimpleWallet { address owner; constructor() public { owner = msg.sender; } modifier ...

Im having trouble reading data from a smart contract I have following js script right here: (bcc-js.js) var contract_address = "0x88e304D8638c31DaC3336917bbE4A152927198D8"; var contract_abi =...

I have a full testnet node running on GCP with Parity. After about a week of having it fully synced, the egress traffic from the server spiked substantially and started sending out 250GB per day to ...

Is it possible to interact with a smart contract with bytecode only (without ABI)? If yes, how can I do this?

Using go-ethereum package how can we read the JSON file of the deployed contract and then get the ABI out of it and then instantiate? I don't want to compile smart-contracts into GO but want to use ...

I am doing a fresh geth 1.9.18-stable sync, which I believe is fast by default. I am keeping an eye on the size of the .ethereum/geth/chaindata/ directory and have noticed that it does not increase ...

I'm newbie studying blockchain and Ethereum. While I'm studying, I've got a question. What will happen in the case of conflict of two different states on smart contract, e.g. from the network ...

When I try to recall the contract after it has been successfully deployed, I type the following code: todoList = await TodoList.deployed() ReferenceError: TodoList is not definede console at ...

I read somewhere that the 'state' is only updated at the end of each block. I've also read that each block contains a specific sequence of transactions, and thus implicitly 'updates' the state within ...

Sorry for the noob question, but Im trying to understand some definitions and clarify the limits between solidity, web3, etc. I have obtained a tx looking like the following from the 0x API: b'{"...

Can you tell me what this piece of solidity code means please? uint number = uint(block.blockhash(block.number - 1)) % 37; Thank you Take care Pierre

I am new to this. So, how do I connect web3.py with Ganache. I've got Ganache up and running, smart contract deployed. I would like to interact with it from, lets say, a python shell. So, this is what ...

Instead of transferring my ERC20 token to my wallet, I accidentally sent it to the contract itself(Here is source code https://etherscan.io/address/0x0bc529c00C6401aEF6D220BE8C6Ea1667F6Ad93e#code) ...

I've seen multiple times Solidity contracts, which are using import "@somename/.../SomeContract.sol" syntax. Here's the example: pragma solidity ^0.5.0; pragma experimental ABIEncoderV2; ...

I need this reply for a large user base prospective, where each second too many request going to that particular contract , so the question is what is write per second limit and what is read per ...

What are you expecting from ETH 2.0? Are you going to use it? According to this article - https://medium.com/the-capital/ethereum-2-0-why-the-transition-is-painful-and-risky-ca0ec12305b3 there Shouldn'...

$("#searchBtn").click(function () { patienttdetailsContract.methods.readPatient(parseInt($("#p_search").val())).call(function (err, result) { console.log(...

I am working on building a coin that will be useful in providing UBI, but need a method to maintain the price of the coin, so that it doesn't fall below threshold. Here is the idea: So every month, ...

I'm building a small dapp to allow users to deploy smart contracts without needed gas, where I'll use GSN or biconomy. I'm not sure you can use meta-transaction services like these for transactions ...

I tried RPC api to connect to Geth/web3 hosted in AWS EC2 using the public IP. But developers have disabled web3 in RPC(HTTP) Web3 api for non local connection. It means that you can only make a web3 ...

I am writing a truffle javascript test and I need to test if a key in a mapping was deleted. After deleting it, its values are equal to '0x0000000...' . How can I test in a truffle javascript test ...

I started to get following error: Fatal: Error starting protocol stack: gap (#3697270) in the chain between ancients and leveldb. What may be the cause of this error? I was able to fix it by syncing ...

pragma solidity ^0.5.0; I get invalid opcode error when trying to estimate gas needed for my transaction from react-native using the following line of code: const gasAmount = await contract.methods ...