All Questions

I signed my transaction and my transaction used the standard structure: *types.Transaction here is my transaction: to := common.HexToAddress(toStr) gasPrice_ :=new(big.Int).SetUint64(gasPrice) ...

Steps to reproduce: Private geth network is running on server1. Deploy contract using truffle and make a few transactions. Stop geth n/w of server1 and copy its entire directory (accounts.txt, boot....

I have a DAPP and ERC20 Token which has an initial supply of 9000 for testing purpose..First step is to login/register into the DAPP where all the information resides..There is an element in the DAPP ...

I have this contract with a mapped array of the struct Item linked to a specific address. I want to transfer a specific array in Item[] to a different owner/address. What is the best way to achieve ...

I'm working with Nodejs application, and using a multi-node setup on different servers. If I have single node end point like http://localhost:8545 I can use Web3 providers as below var web3 = new Web3(...

I am looking to retrieve the current price of a token from Uniswap. I have successfully used the ChainLink oracle api to get the price of BTC/USD, but I want to now integrate Uniswap price feeds. I ...

We're looking to migrate an existing public Ethereum contract where we have hundreds of ERC20 token holders to a new contract on the public OMG network (to mitigate txn fees). What's the best way to ...

Context: We are creating a smart contract which integrates Uniswap DEX for swapping Tokens to ETH. We need to make sure one swap does not impact the token price more than 3%. We are in need to write a ...

Facing an issue while working multi-http-provider. When I write var Web3 = require('web3'); require('multi-http-provider'); It throws an error uncaughtException : RangeError: Maximum call stack size ...

The private network is using the PoA consensus algorithm with Clique protocol and gas price and limit are set. If all accounts had large amounts of ether granted to them on creation , how would a ...

Since Solidity functions can't accept String Arrays as arguments, I'm trying instead to pass in a long comma-delimited string, and then convert it to an array of strings on the fly. I'm close - but ...

I currently have a problem with metamask on android mobile. I can no longer access my account, when I enter my password, I have this error: Syntax error: Unexpected token r in JSON at position 0 I ...

I want to know can I use smart contract as a multiple transaction...some ether input from some addresses transfer to some other addresses as outputs I read this article but I did not know https://...

From our custom mobile app, we would like to allow users to connect to Metamask and fetch their Ethereum account address(after their consent). For this, we need to navigate user from our mobile app to ...

The @openZeppelin's ProxyFactory.sol("@openzeppelin/upgrades": "^2.8.0",/"truffle": "^5.1.51") is used in development of proxy contract: pragma solidity ^0.7.0; ...

I just witnessed something amazing that I didn't think was possible before. I was under the assumption if that you try to submit consecutive transactions, the latest transaction with the highest nonce ...

I am finding some weirdness with the Truffle test suite where it recognizes an event if it takes only an address argument, but if it takes an address and a string truffle does not pick it up in the ...

Is it possible to pre-set the length of the set of an EnumerableSet.UintSet type? For instance, if I declare this mapping: mapping (address => EnumerableSet.UintSet) private agentTickets; and then ...

Complete noob here. I'm developing a dApp that functions on top of a private clique PoA blockchain (using geth). The project should be viable in a production environment and allow nodes to transact ...

I have just started mining and using ethminer on my mac using the Blackmagic eGPU and I am getting the following output, which doesn't seem correct:- m 18:21:12 Speed 6445.46 Mh/s gpu/0 ...

I am trying to write a smart contract with a function that receives an ERC20 token (i.e.: DAI), but the transaction to call this function is always failing. Let's assume I first record the ERC20 ...

I want to create a wallet/gallery for NFTs and I was wondering if it could be possible for the user to send NFTs made in other providers/minters to burn in my platform. The thing is that I want to ...

I have created a set of contracts that will shortly be undergoing an audit. It's a DeFi platform that is intended to hold real value. The project began as a fork of a fairly old project, that uses ...

I have an all code defined in my smart contract of user registeration..It's working great,But the issue is, it takes gas fees to register user which is reasonable if you want to write some data on the ...

i created a new account in private chain. But the new account value is zero. How add value to the account? Thank you very much. i install web3.js 0.20.6. geth version: 1.9.23. when i use eth....

When I am calling this code(it's a test code related to the bigger contract, but the same problem can be observed here) I am receiving an error - ParserError - expected ';' but got '.' . pragma ...

I wanted to test my code functionality with the Mocha Framework, but every time it responded me with an error, not an assertion. The specific error was: Error:cannot find module "ganache-cli&...

I have opened an instance of ganache at localhost port 9545 where I can connect with web3.py. However when I am trying to perform a transact using the below code: w3 = Web3(Web3.HTTPProvider('http://...

Is transaction "status" flagged inside the block when it's mined? Like if a transaction is mined but failed due to out of gas or not meeting contract conditions, is the transaction marked as ...

When we call sendSignedTransaction from web3, my understanding is that the transaction is broadcasted to a provider (either a hosted node or your own node) and added to that node's mempool, assuming ...

I am trying to run someone else's code from GitHub and I encounter this issue. It said that Invalid implicit conversion from uint256 to bytes32 requested. Please have a look on this code. function ...

I setup a Medalla-Geth-Node and a Eth-2 node (Teku) and went through all the steps in the launch pad. My status went from "Deposited" to "Pending" and currently the beaconchain-...

I wants to calculate annual percentage yield for a token pair listed on uniswap like this. Is there any API which I can use to retrieve the value? How can it be directly calculated?

i know that price impact implies that the difference between market price and estimated price due to trade size. say i have a pair: cat token and dog token with pooled cat : 0.999992 pooled dog : 1....

I have a user registeration logic defined in solidity which used to work fine when I set an registeration fees of 0.5 ETH for testing purpose.But now, when I remove the register fees, I'm not able to ...

I am developing an online store BNB as a payment. Customers will sign transactions using Metamask and then frontend code(js) need to post call to our backend server with the txHash, and then we will ...

I'm working with genetic algorithms and I need to create a population. Currently I have this function: /// @notice Create a new individual function createIndiv(uint _popSize) public{ for(uint i = ...

Maybe it's a newbe question but I notice that when I restart Geth it always "rewind blockchain" ? Why is this ? Here is example output: INFO [11-08|22:02:47.152] Starting Geth on Ethereum ...

I have a simple sol file message.sol pragma solidity >=0.5.10; contract Message { string public message; constructor(string memory initMessage) public { message = initMessage; ...

My contract does like this; pragma solidity 0.6.2; import "@openzeppelin/contracts/token/ERC20/IERC20.sol"; import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol"; import "...

If I transfer the ownership of a contract to another contract using following truffle command await token.transferOwnership(someOtherContract1.address); I already did above Now I want to transfer &...

So im trying to write a smart contract that involves using Uniswap. I would like to test my smart contract and was looking into setting up uniswap on my local ganache server, but as I am new, a few ...

I've worked with upgradeable contracts before using zeppelin's upgradeable contract pattern. However, I found out that if I try to fetch the implementation contract address through a contract call, I ...

I am new to this and just have some arbitrary questions regarding upgradeable smart contracts. If a Developer would update his contract, could he modify all mappings / variables entirely? Wipe ...

Can you please tell why do we have to approve ERC20 tokens before sending them? contract Transfer { function version1() { ERC20(someToken).transferFrom(msg.sender, address(this), 122); ...

pragma experimental ABIEncoderV2; pragma solidity >=0.4.18; contract Record { struct MedRecord { string password; string name; address patient; address[] ...

It seems[1] they do: (0.997 * amountIn * reserveOut) / (reserveIn + 0.997 * amountIn) From my understanding it should be amountIn * price, which with fee becomes ((1 - fee) * amountIn) * price. Now, ...

Okay, I have no idea what just happened, but I think I just lost like 50% of my coins. I sent Link from my ledger to binance, and when I checked an hour later, it said failed both on my ledger app and ...

I need to query this endpoint '''https://******com/api/payments/{payment_id}/refund''' Because it is a post request, I assume that the payment_id param needs to be in the body of the request. How do I ...

I know a little about Ethereum and how it works, but what am I wondering is that why we exactly need a transaction to be stored in Ethereum blockchain? What's confusing for me is that Ethereum client ...