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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Will Dapps in production be able to buy and use SaaS solutions?

SaaS services help centralized organizations or apps solve their business problems. For example, Google Apps offers startups as an easy solution for company email and document storage. The sales ...
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Would this three address Ethereum transaction be possible through Geth?

I would like to store an amount of Ether in an specific wallet, likely a wallet generated in Geth. From there I would like to send the correct amount of Ether, I suppose in the form of Gas, or ...
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Is there a way to halt a transaction from being confirmed until an event occurs?

For example, user 1 sends a transaction to user 2, but that transaction is not able to be confirmed until an event occurs, allowing the transaction to be confirmed and thus sent into user 2's wallet. ...
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DB - How do I roll back to a block height?

I was informed on this post that I was, indeed, on a fork. My client starts syncing and encounters a discrepancy with my local DB copy. My peers then vanish. In my case, it would be a great hassle if ...
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I have token in eth I'd 0x5ae3876e3f26b6c99895b1ff9e094e6e6992b88b

Please help how can I transfer my tokens from 0x5ae3876e3f26b6c99895b1ff9e094e6e6992b88b to my another eth wallet account at 0xfdC1049162dd014AF7Fb11099DAe8F2A09f330e2.(both are my wallet ids). But ...
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Event log history is not getting generated ropsten test network

I want to view event log history in my html screen. But I am getting below error in console. Can any one please look into this. I am new in blockchain and this is the first blockchain code I am ...
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315 views

Local ethereum node contain two different blocks but with same height

I am using geth node and found 2 different block with same number eth.getBlock("0x162ae4b189f77ed65d0be270aa8dea08d4e7dcd70432a7d1fd4e6b0fb1b301d6") { difficulty: 1001546728, extraData: "...
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How do I verify the integrity of my local chainblock data?

If I suspect local data corruption, is there a way to verify that my blockchain data is valid and will not affect my Ethereum work and transactions? Example: I switched to a self-compiled version of ...
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1answer
700 views

What is the best parity configuration to run a full archive node on raspberry pi?

I am using a raspberry pi to download the archived version of the blockchain with parity. I've started parity with parity -d /home/xxx/data/Ethereum --pruning archive --public-node However, the ...
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Ethereum performance when fetching transactions from blocks

I need to fetch the completed transactions from the ethereum blockchain ledger. At the moment I am retrieving individual blocks in order to fetch the transactions using web3.eth.getBlock synchronously....
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203 views

Can't open ethereum wallet when blockchain is on my SSD

After a lot of searching I found how to set the datadir path to download the blockchain on my SSD instead of my :C/ drive since that's almost full and now that it's downloading the blockchain i would ...
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1answer
140 views

iOS node not syncing with private BKC

I use the Geth framework and Swift 4 to boot a node inside an iOS 11.0 app. This node connects to my local BKC (to 4 nodes to be precise). Here are some tests I made : if I start 3 computer nodes ...
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102 views

Setting balance to an account

After i created a wallet for a user i want to modify his balance, how could i do that without setting the account address' balance in the genesis, I'm using quorum blockchain with web3j. Thank you!
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1answer
70 views

liaison entre web3 et nodejs [using web3js and nodjs]

Bonjour, j'ai développé une app avec nodejs et je voulais la transférer vers une dapp en intégrant le web3 librairie. En effet j'ai crée les smart contract il le me reste juste la façon de faire la ...
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118 views

How to test forked block on local machine?

Read this article How can I reliably induce a blockchain fork for testing purposes?. Example from that thread is outdated, and need to be refreshed. First my step is create initial chaindata from ...
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Use-Case: building a small test-network, did I got it right?

I've to implement a simple use case and I'm not really sure if I understood everything correctly. What I'm trying to do is to build up a network with a few Raspberry-Pi's, running as full-nodes. ...
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180 views

How to configure Azure STRATO Blockchain LTS with Visual Studio?

I'm learning all about Blockchain but I wanted to make an example of smart contract, i followed this tutorial, but I can't find much about how to integrate Azure Strato Blockchain with my application ...
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219 views

Ethereum raw data files folder

Where is the folder on Mac OSX where Ethereum put raw blockchain data? I find only *.ldb files, but as I understand it is only the index of full database. For example, in Bitcoin there is blk*.dat ...
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2answers
377 views

Smart Contract - Update implementation using a Relay with delegateCall

I know that smart contracts are supposed to be immutable and that's the whole point, but to expect someone to implement a logic that never changes (no upgrade or no bugs) from day 1 is also ...
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250 views

Parity scheduled transaction stuck at submitting

I scheduled a transaction for the BAT token after block 3798640. It remained pending before the block for hours, then submitted about an hour ago, see Tx local viewer screenshot. Anyone know if this ...
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247 views

Is there any benchmark about the speed of blocks search engines?

I want to know the performance of search engines such as blockchain.info, smartbit or blockr.io I know that they are very speed but I want a real benchmark that gives the actual speed (in seconds or ...
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108 views

What is a sealer and what is the difference between Ethhash, NoProof and BasicAuthority sealers?

Default sealer in cpp-ethereum is NoProof: https://github.com/ethereum/cpp-ethereum/blob/43bae2c78e2a968ef4eb37bec2da4d9b85fa2392/libethcore/ChainOperationParams.h#L73 But I don't understand what is ...
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205 views

Ethereum usage for financial transaction

I am new to ethereum blockchain, and i have following scenario of simple money exchange to be implemented: Consider three account Sender(USD), Receiver(EURO) and Provider. Where provider is account ...
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280 views

private Ethereum Network Uncle Mining: blockchain forked from a node even that node still connected to the network

I have a private Ethereum Network. It was working without any problems when I had a single miner. But when number of miners increase, I am faced with the following problem: The way I have started my ...
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751 views

How to continue to watch the `Events` from the point `geth` was closed?

I have a private Ethereum network. The bootnode(main node)'s goal is to watch Events and if a new Event is generated than trigger a contract's function that I want to run. The key point is triggered ...
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1k views

Is my address valid?

I'm using Blockcypher's API (https://dev.blockcypher.com/eth/#generate-address-endpoint )to generate Ethereum addresses. One such address that has been generated is :- Public Address (...
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58 views

What do the progress bars on the Alethzero “blockchain download” window mean?

I'm exploring Alethzero. What do the progress bars in the "blockchain download" window mean? I'm seeing this: I'm assuming this relates to the progress in dowloading the blockchain but I can't work ...
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270 views

How is transaction finality correlated with transacted amount?

It was argued by Vitalik Buterin that transaction security can be a function of the amount the transaction carries. This is because of the economics of attacks. How many block confirmations would you ...
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1answer
169 views

Can someone download and run a local version of my contract?

Say I have a smart contract the preforms a specific function and is used in a decryption process off-chain. Would it be possible for Molly to download the entire contract and run it on their own local ...
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1answer
629 views

problem when deploy smart contract in Quorum using web3j

I'm using web3J when i try to deploy contract i get Error processing transaction request: Non-200 status code: &{Status:400 Bad Request StatusCode:400 Proto:HTTP/1.1 ProtoMajor:1 ProtoMinor:1 ...
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1answer
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ERC-2309 Minting Multiple ERC-721 Tokens in one Transaction

Anyone know how to work with ERC-2309? It's an extension to the ERC-721 Token standard and it's supposed to make it possible to mint a large number of ERC-721 tokens (meaning 100's or even 1000's of ...
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1answer
16 views

Blockchain without cryptocurrency

I am new to blockchain and am having certain doubts. Can we substitute cryptocurrency to carry out blockchain operations in any way ? Actually what i feel is that the volatility in cryptocurrencies ...
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What is the best practice to receive ether from external accounts?

I want to create a smart contract that receive ether from external accounts and pay them some profits monthly. I need to receive ether from them. What is the best practice in this regard? Whether the ...
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5 views

How to show token balance from a ETH address in my Android App?

I have an Android App and I want to show the balance of an especific token of the user wallet Address IE: show how many CHAINLINK are holding the user on his wallet Thanks in advance
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20 views

Ethereum geth mainnet blocked on “Looking for peers”

I installed Geth for setup a ethereum node on my linux server and use it on my RPC API. The problem is, Geth is posting "Looking for peers" forever, I don't really understand why. This is ...
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Decentralized Identifier - DID method Registration

I am trying to register a new DID method like 'DID:mymethod' for my specific use cases. I am planning to register this new method under the Ethereum Blockchain. But, I am not sure who do I approach ...
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23 views

openethereum node disk usage

Using openethereum to sync the eth blockchain, after synced and now the disk space keeps growing 20G per day. The .log file in the db folder keeps growing. After restarting the node, the space will be ...
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truffle init function is showing an error on my Ubuntu 18.04 system

When I execute the truffle init command on my command line(Ubuntu 18.04) it's showing me the following error. ubuntu@ubuntu-vbox:~/block_chain/Ballot1$ truffle init Downloading... Error: Truffle Box ...
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Gas estimation failed error:Can someone help me to resolve this error,Many thanks

I'am facing this error:gas estimation failed:"gas estimation errored with a following message .the transaction execution will likely fail.do u want to force sending?gas required exceeds allowance(...
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16 views

blockchain sync failed and stuck

My machine was crashed and rebooted, but after rebooting, geth sync repeatedly failed at a block, I checked the block number, hash is right though, what should I do? INFO [08-08|09:54:23.184] ...
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What would be good result measures in Ethereum

I'm thinking of a way to present relevant results measures for my blockchain. I can see how for hyperledger is interesting to present (transactions per second x block size) or (latency x block size). ...
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block syncing current is smaller than starting why?

I'm sync the chain after a power cycle, so current is behind highest for sure, but I also saw that current is falling behind starting block number, how is this possible? starting is the highest on ...
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15 views

Creating a system with multiple blockchains where they can interact with one another?

I'm currently trying to create a sort of proof of concept where I would like to create a system of blockchains for individual accounts to track their balances. The idea is to have a snapshot of their ...
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Success transaction of Ethereum not reflecting in my coinbase wallet

I transferred ethereum of 0.074 to my coinbase wallet. it is showing success transaction but it is not reflecting in my coinbase wallet, why?
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1answer
40 views

How to make this interact with metamask

I've been trying to make my contract be callable by metamask (so a popup will occur telling the user to confirm) but it does not seem to work, heres what I have come up with so far. Can anyone give me ...
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23 views

Web3 IPC provider connect?

I am using Infura web3 provider to connect etherum but I want to use IPC provider(more secure), How to use IPC provider in ethereum web3.
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36 views

Insufficient funds for gas * price + value in Ropsten

I write API for smart contract but its shown error "Insufficient funds for gas * price + value"? My try I have increased my address balance but it's showing the same error. I have changed my ...
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16 views

Insert data whithout overwriting the already stored whit the same address

i'm new to solidity and i'm developing an easy app. This is the contract i'm working on. It's all functioning but i need to: do some sort of function that return me all the array value whit the same ...
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36 views

How do I get the available reserve size for a given token on Kyber and Uniswap(V2)

I am doing arbitration with some measure of success; but I suspect I am running into edge cases where the available reserve size is less than what I am trying to buy or sell. Something like this: ...
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14 views

Blockchain interoperability

i hope that you are doing well! I wanna build an Blockchain interoperability approach based on side chain and i don't know how to start, so if someone can help me please don't hesitate to text me i ...

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