All Questions

Go Ethereum's documentation for running the command line program is at https://geth.ethereum.org/docs/interface/command-line-options There it specifies the --syncmode option with the explanation: ...

So, I've been using MetaMask to try app.compound.finance and everything went well. I've deposited a small sum and connected the app to the wallet. But a few weeks later I decided to deleted the chrome ...

How to make this kind of query using my 200kb/s second Internet connection speed ? With such speed, there’s no possibility to run an archival node (except maybe with a service allowing to download ...

I am considering to set the blocktime to zero (clique.period:0) in a permissioned private blockchain with known but untrusted nodes. The reason to do this is having a minimum transaction process ...

I'm trying to get a little example working with ECDSA.sol here: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/cryptography/ECDSA.sol This contract: Generate a random(...

Is there any way for a remote webserver to connect to a USB device using serial? If so, why did major hardware wallets use a Chrome Extension as opposed to a backend server for connection? Ledger used ...

All the source code I could find (to date) has declared transfer, transferFrom, approve, approveAndCall as public and not external. Although external can be used, what is the reason behind not using ...

Does anybody help me figuring out why I am getting failed transaction here?What does this error means? Few days back,with the same line of code,I was able to successfully send transactions. An update:...

After Creation Contcact and receive ETH it answer messagem ERRO and Block Owner It was made with CODE Pattern when Eth was watched like Model to ERC 20 How to cancel or erase contract and Get Back ...

I'm trying to call a function from another contract and need a way to accommodate errors. Say contract A has the method getBalance: function getBalance(address x) public view ...

New ERC1155 standard which is thought to be an improved version of ERC721 and ERC20. But I see many projects still prefer ERC20 or ERC721 standards. If so, do you know any projects implementing ...

What are the main differences from Ethereum's makerdao dai stablecoin to EOS's equilibrium EOSDT stablecoin? And are there other stablecoins like these two that are decentralized and issued via a ...

I have a fairly large contract that I must create on Kovan network for testing. There is fairly weird behavior occurring when I am trying to create the said contract. Behavior being: whenever ...

in my solidity code I create a tracking-contract and auction-contracts out of a factory-contract. The last function 'a4_Payment' of the auction-contract should be triggered out of the master-contract ...

I am now deploying smart contract using ganache localhost:7545, i want to use infura ropsten account to deploy. Most examples uses Metamask, but i want use own ethreum wallet. How can i use to deploy? ...

Description I'm trying to deploy a contract to rinkeby network, but everytime I like to deploy the contract it throwing error as invalid sender. Compile code const path = require('path'); const fs =...

We are currently testing functions on Ropsten test network and have an issue regarding the gas usage. Our functions sometimes use 12 gas more and we can not fathom why that would be the case. To test ...

Using web3js v1.2.1 const contract = new web3.eth.Contract(abi, '0x29...'); const amount = 1 * 10 ** 18; const data = contract.methods.transfer(recipient, amount).encodeABI(); I get error : invalid ...

I run: geth --rinkeby --rpc --rpcport=8545 --rpcaddr=192.168.1.37 It works in console: geth attach http://192.168.1.37:8545 > eth.syncing false > eth.accounts ["...

I import another contract Hello.sol in contract test1.sol, but after deploying it, only contract Hello's function is displayed in the run interface, not contract test1's function???What is wrong?What ...

Are there any voting based approaches where voting would happen off chain, via signed messages, but then the result could be indepedently verified or even stored on chain? Voting rights are based on ...

Simple question but I couldn’t find the answer. Is it the datacopy precompile? and if yes, what it does?

interface AgreementInterface { function newAgreement(string _leaser, bytes32 _houseId, string _houseAddress, string _describe, bytes32 _signInfo, uint256 _rental, uint ...

I'm trying to generate java wrapper class of solidity smart contract using truffle but not getting wrapperclass.java file Here is an command which i've used to generate abi/Json of that contract ...

I am trying to send an ERC20 token with the following code via web3.js. It was working until a week ago and then it stopped. Am I doing something wrong? Upon clicking it no longer interacts with ...

Render props were added after React 16.3 and the github readme for drizzle-react suggests to use them. The problem for is that there is no updated documentation (other then the small example in the ...

I had asked this question before. I looked carefully at the exchange section, which I advised, and I think there is no problem with the exchange section. At least in my opinion there is no problem and ...

function purchaseWithToken(uint256 amount) public { require(amount > 0 , "Purchase require amount > 0"); require(_balances[msg.sender] >= amount , "amount not enough"); _balances[...

How to implement a new custom consensus algorithm in a network.

Seen a paper on Proof-Of-Learning and wanted to know-how the consensus works and how to implement it in ethereum?

I am looking for a new era of products that leverages the potential of Machine Learning and the blockchain, Thinking of different aspects of Blockchain which can be improved with the help of machine ...

I am trying to get a return value from the payable function, the idea is a user must pay the fees and in return, he will get his special code. My JS test code is as follow it('get special code ...

I don’t understand how it works. I created a contract with a constructor with parameters. But I don’t understand where to pass these parameters to the constructor. Or I need to set params after ...

I have a contract where the hash value is also the key to unlock the money. As the full ecrecover parameters are fetched from transaction parameters, and it was compiled in 2016, it is vulnerable to ...

I have to access methods of one contract from another contract body. How can I realize that using just a address of first contract? contract KittyShelter{ address KittenRegistry; //Here, ...

Is there an Ethereum test blockchain (similar to Ganache) which prioritises calculating transactions and creating a local blockchain 'db' as quickly as possible? Requirements: - Calculate ...

As stated in the wiki: Note: An uncle doesn't contain individual transactions. I would still like to extract transactions from uncle blocks. Is there any method available for doing so?

at the moment I am experimenting with the factory/child-logic in solidity. With my factory contract I am able to create child contracts in which an auction is executed. Now I want to return a variable ...

A CDZC coin basically fork of PIVX . I am trying to send coin via rpc calls. Successfuly created RawTxn, SignRawTxn but unable to SendRawTxn. `await rpc.listunspent().then(async r => { ...

I am trying to get Sage to generate all graphs with 7. I typed in the following: g7=[g for g in graphs.nauty_geng('7') ] I’d like to save as g6 data typeI file. How to do ? I want to use the g6 ...

Last block with latest transaction was mined 4 hours ago. Of course, other explorers can see the latest ones but I need the Etherscan feature of accessing the details storage change of transactions. ...

Is it generally better to define a contract instance once, then pass it through your components like... class Parent extends React.Component{ constructor(props){ super(props); ...

I have a contract on Ropsten, and when I do this is python, I get a result: result = contract.functions.getLastUpdateTime(0).call() So I know the abi is there, the address, etc. There's another ...

I'm using the EVM One back-end with ewasm/geth according to the following instructions. Geth seems to be starting up as usual with the following command: geth --vm.evm=./libevmone.dylib How can I ...

I want to limit transaction pending time to 5 seconds, after that the transaction considered as failed; does --txpool.lifetime solve the problem ?

I want to watch for fileViewed event and it throws TypeError: market.FileViewed is not a function in marketplace.FileViewed{ ^ My solidity contract: pragma solidity ^0.5.0; contract ...

Sorry for the silly question. I have a div container "product-card" , I want to loop the number of my deployed smart contracts time. every time when I loop I want to clone this div container and ...

When we put a low nonce in transaction options we got "nonce too low", but when a put a big nonce (bigger then transaction count) we got anything why ?

I want to change the message in connection request window using web3js. I have attached screenshot here. kindly check it.

is it possible to know what is the reason of transaction error from "error" object (nonce, insufficient fund ..) is there status or something to test using it ? Geth error message is generic, I ...