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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Syncing block chain

I was syncing the blockchain using something like geth --fast --cache=2000 -jitvm. It reached about block #3819000, and then it did something odd. It stopped saying "Imported x reciepts" or "...
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In a private blockchain network, can we delete the first N blocks and reassign the N+1th block as the genesis block?

I am aware of the data loss caused by deleting the first N blocks. But I am curious to know whether such a task is possible or not. If so, how to practically implement it? ( I am using go-ethereum. ...
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671 views

block download canceled, geth 1.5.9 would not download blocks

when starting out geth I cant download past block 1292880 does anyone have any idea why it would not download any more blocks?
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How to get raw binary data from ethereum blockchain?

I want to get ethereum blocks as binary data and parse them manually to get raw ethereum transactions. Are there any good manuals how to do it? UPDATE: how ethereum genesis block (at height #0) looks ...
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255 views

Synchronisation issue on Mainnet, testnet and private network

I am just unable to synchronise on any kind of network either main network , testnet and not even on private network. I have updated my geth instance to a newer version - Geth/v1.5.9-stable-a07539fb/...
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Ethereum send transactions are unsuccessful when I run the node and miner in same machine

I have started the Ethereum client using the Go Ethereum. And also started the Ethereum miner on the same machine. Now node and miner are running in the single windows function. If I try to send ...
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176 views

Public-of-chain using proof-of-authority, where authority is defined as the amount of work on your public key

I'm wondering if there would be benefits to create a public blockchain based on the same algorithms used for private, proof-of-authority blockchain, except replacing the concept of authority by the ...
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506 views

In parity, how can I delete the last blocks I downloaded without corrupting the database?

I have found the blockchain data in parity. I go to overlayrecent folder and from there to the db folder. It looks like the blocks are the .sst files. How can I delete the last blocks I downloaded ...
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246 views

Connection between two blockchains

I am looking for an approach to creating a connection between two blockchain-networks. I found out that I can use oracles to get data from extern systems (= second blockchain-network). But how can I ...
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282 views

geth taking a long time to mine a block

I'm using the embark framework to deploy some smart contracts to a private Ethereum network. The problem is, the network behaves differently on separate machines, even though they're similarly spec'd -...
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Mist 0.8.5 & Geth 1.5.0

Current Mist is 0.8.5 and it runs geth 1.4.17. How can I initial geth 1.5.0 by Mist 0.8.5 without manually start Geth 1.5.0 first ? It's all to do with instruct geth that chaindata is on an external ...
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58 views

Distributed application with client side stuff?

I would like to write a smart contract which allow users to publish forecasts and then vote which forecast was the best. Adding a forecast should be done manually by user. But I would like to automate ...
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870 views

Comparing Ripple and Ethereum

What advantages and disadvantages does Ripple have over Ethereum?
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89 views

Chaindata behind in blocks

My Mist wallet shows Im synced but when I go to the chaindata folder it is about 130000 behind.Does anyone know why this is. I do not seem to have a problem with geth or mist but curious why the ...
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1answer
30 views

How to download the blockchain of a single ethereum contract’s address?

The blockchain required to run ethereum is several Terabytes large. This means more than 9 years would be required to download it with my connection speed. In my case, I just want to know if the ...
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30 views

Returned value arent valid did it run out of gas?

After migration command line (truffle migrate --reset --network rinkeby), it is deploy. However i couldnt see at etherscan website when i enter the contract address. Should i see? Whatever then i ...
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1answer
29 views

Are the timestamps of blocks for Ethereum only accepted when they are monotonically increasing?

Are the timestamps of blocks for Ethereum only accepted when they are monotonically increasing? If yes, why? And why other blockchains like Bitcoin and other blockchains with shorter block time can ...
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How to Read Construction information?? (from blockchain develpment with go)

pragma solidity ^0.5.10; contract Simple{ uint256 data; string male; string name; string id; function getdata() view public returns(uint256) { return data; } ...
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2answers
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How to find out the number of Validators of a transaction if i have its transaction hash

I want to find out how many validators have validated my transaction.My transaction has is 0x051430dc5cd84c44954e43b25f8709c9c1a1c634f384ec6dd7610f6f945732e1 can anyone tell me how many validators ...
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1answer
49 views

Implementing ERC721 Marketplace

I'm working on a project where I need to implement an ERC721 marketplace. It doesn't work for some reason and wanted to know if I'm doing everything correctly. The way I approached this was: The ...
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17 views

Head of blockchain fall back to 0 after unsafe shutdown, how to reset it to the latest?

System information Geth version: 1.8.27 OS & Version: Linux Docker version: 18.09.0 Background gcmode is full, syncmode is fast. Single node in private network. datadir mount to docker volume. ...
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139 views

Problem connecting web3 via websocket to node with nginx

we are trying to connect to a geth node via WebSockets to be able to subscribe to contract events. This node is created with docker and this docker uses nginx as a proxy. We can connect easily with ...
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46 views

Solidity: TypeError: Member “unbond” not unique after argument-dependent lookup in contract super EthGatedMarket

I'm getting this error: TypeError: Member "unbond" not unique after argument-dependent lookup in contract super EthGatedMarket. super.unbond(msg.sender, gatewaySpecifier, quantity); ^----------...
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How can I combine Quorum and Zero Knowledge Range Proofs

How can I combine Quorum and Zero Knowledge Range Proofs I have 20 years of experience at java JEE coding, and 10 years in devops as well, but no experience with blockchains, or the Go language. I ...
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Could the parity-ethereum client incorporate doing range proofs in the ethereum blockchain?

I want to be able to prove that I have stored a number that is in the range of a minimum and maximum value, (a range proof) without revealing the number, and put the value into the ethereum blockchain,...
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1answer
51 views

Static difficulty in 1.8.27 for local network

I am having trouble getting geth 1.8.27 to have a static difficulty on a private network. I followed the instructions from here. But when I test it, the difficulty still increases. I tried again, ...
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1answer
109 views

Access deployed smart contract using web3.js

I am new to Etherium smart contracts. I have created a smart contract and deployed it on https://kovan.etherscan.io. Now I am trying to access this contract from node js. below is my code but I am not ...
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104 views

Parity syncing in archive mode stuck at block 4839206

I am running Parity inside docker in pod in Kubernets on Google Cloud. The pod is using disk with 2700 GB for storing Ethereum blockchain, and currently disk has about 2100 GB free. Unfortunately for ...
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3answers
293 views

Can't compile old solidity contracts(version 0.4.17)

I'm new with blockchain development. I'm working on an old project which use solidity 0.4.17 and truffle ^4.0.0-beta.2; These versions were in the package.json file of the project. When I installed ...
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1answer
205 views

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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1answer
25 views

What is the advantage and disadvantage of deploying Erays on Ethereum?

I have read this paper, Erays: Reverse Engineering Ethereum's Opaque Smart Contracts. They proposed this reverse engineering tool for Ethereum smart contracts. it will take as input a compiled EVM ...
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86 views

Transaction submitted through Infura, but not from local node

So, I have a Rinkeby fast sync on my server. When I try to interact with my contract and transfer something, geth says "Submitted transaction", but then I can't find it using its hash on etherscan. ...
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46 views

What actually a block contains, is the data inside it a virtual or physical entity?

My understanding of a block in blockchain is that it is a data structure that contains information like Block Size, Block Header, Transaction Counter and then Transactions. Deeper in the Block Header ...
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1answer
172 views

Performance Analysis of Ethereum Clients Geth and Parity

I want to do performance analysis of Geth and Parity. I want to run 1000 transactions serially on each client and want to get transaction processing time for each transaction. How can i get these ...
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1answer
75 views

How can I execute transferFrom function in node js

There is solidity erc865 code function transferFromPreSigned( bytes _signature, address _from, address _to, uint256 _value, uint256 _fee, uint256 _nonce ) public ...
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1answer
23 views

is there any method convert mutiple params to one bytes in web3js ,and then get these original data from bytes in solidity?

eg: the params in js code below,how to convert to one bytes var min=100; var max=100000000000; var price=1000000000000000000000000000; var name="john"; in solidity code below,how to get original ...
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8 views

How many Times I can Bid on Same domain name and Is There any way to increase bidding amount during auction

Is it Possible to increase my bidding during ENS auction period ?How can see highest bidding before reveling period. How many times i can bid for the same doamin in 3 days aution period
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107 views

Connection of web3 with Ropsten

How do I connect my web3 to ropsten network. I know how to pass the url of ropsten netwrok in web3 instance in my script tag but when i try to to console.log(web3.eth.defaultaccount) it gives me ...
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How to get live mempool transactions whitout full blokchain

I just want to analyse all mempool txs in realtime. I cant use an api because after several requests my ip gets blocked for some minutes, so I dont get the txs in this time. Thank you for help.
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36 views

Peering over a direct L2 link without IP addresses

As part of a big solution incorporating blockchain and data networking, I'd like to know how would 2 nodes establish a blockchain peering on their direct L2 Ethernet Link that has no IP addresses ...
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75 views

How can I run smart contract locally on my computer?

We all know that Ethereum nodes can run smart contract. But I'm wondering whether can I setup contract run-time environment from Ethereum source code locally so I can run smart contract without ...
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44 views

Ethereum Blocksci parser tool

I need a blocksci parser for ethereum. I am using https://github.com/citp/BlockSci for bitcoin . Is any similar blocksci parsing tool for ethereum?.
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28 views

When locate a block with both the hash and block number?

In the go-ethereum code, I see functions use both the number and block hash to locate a block. Why is that? Isn't block hash enough? An example function: https://github.com/ethereum/go-ethereum/blob/...
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simulation or performance evaluation with Ethereum testnet

I was if you could help me about simulation. How can I simulate the performance of my following IoT-based Application with Ethereum testnet? In my senario,there are some nodes that store sensor data ...
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Read args object from particular block transaction in truffle console.

Hi I have question on how to read args from specific block transaction that are passed when event was called. I have triggered an event, my block is created and i got transaction tx. In the ' Logs: ' ...
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147 views

Same Block Received More Than Once With Same Block Parameters

Use Case: I am implementing a deposit system where I will get a block as it is mined and parse transactions to check for a deposit of Ether or a specific token. Getting the same block twice will ...
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515 views

Total number of state entries

I am syncing my ethereum blockchain using the default syncmode. I want to know how many total state entries are there because currently the highest block is 6544578 and the number of pulled states i.e....
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Not able to Get the response from the function call from Node Js Service Using Web3@1.0.0-beta.36

I am deploying two contracts A and B using Web3(1.0) and solc. My Solidity file looks something like this: pragma solidity ^0.4.21; contract A { uint public value; constructor(uint newValue) ...
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95 views

What are some fullnode health indicators in geth? (mgasps etc.)

I run a few ETH fullnodes using the Geth implementation, and I'm curious about some of the metrics, specifically mgas, mgasps and how they reflect the health state of the node. Here is the output of ...
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Why is my private ethereum network stuck at “Recalculated downloader QoS values” while trying to mine?

I'm using Mac OS High Sierra version 10.13.6 My customgenesis.json file is this. {"config": { "chainId": 15, "homesteadBlock": 0, "eip155Block": 0, "eip158Block": 0 },"nonce": "0x0000000000000042","...