Trending questions in Blockchain

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Not able to invoke a contract in Ethereum Private chain using geth

Hope this helps: contract mortal { /* ...READ MORE

Oct 22, 2018 in Blockchain by Omkar
 • 69,180 points • 1,523 views
0 votes
1 answer

eth.getTransactionReceipt returns null

It looks like there's an issue with ...READ MORE

Sep 25, 2018 in Blockchain by slayer
 • 29,370 points • 2,684 views
0 votes
1 answer

How to get value from solidity contract using java?

web3j caters for this very use case. It ...READ MORE

Sep 28, 2018 in Blockchain by slayer
 • 29,370 points • 2,554 views
0 votes
1 answer

Invalid method parameters for eth_sendTransaction

params needs to be an array, try {"jsonrpc":"2.0","method":"eth_se ...READ MORE

Sep 28, 2018 in Blockchain by digger
 • 26,740 points • 2,546 views
0 votes
1 answer

UnhandledPromiseRejectionWarning: Insufficient funds error in Ethereum: NodeJS web3

sendSignedTransaction returns a promiEvent onto which you can chain then and catch: web3.eth.sendSignedTransaction('0x' + ...READ MORE

Oct 15, 2018 in Blockchain by Omkar
 • 69,180 points • 1,807 views
+1 vote
3 answers

What is the pattern for handling throw on a Solidity contract in tests

In my opinion the cleanest way is: it("should ...READ MORE

Sep 25, 2018 in Blockchain by Lupin
 • 2,568 views
0 votes
1 answer

Intrinsic gas too low and exceeds block limit

If you are talking about the public ...READ MORE

Aug 29, 2018 in Blockchain by digger
 • 26,740 points • 3,830 views
0 votes
2 answers

Check Bitcoin Balance with mybitx api https GET url

You can use the PHP Requests library for an ...READ MORE

Sep 17, 2018 in Blockchain by Lalit
 • 3,069 views
0 votes
2 answers

Ethereum function completed not event not showing up

Oh ya. I was passing unit but ...READ MORE

Oct 24, 2018 in Blockchain by slayer
 • 29,370 points • 1,361 views
0 votes
1 answer

Hyperledger Composer: How to save deployments?

You are losing your deployments probably because ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 1,185 views
0 votes
1 answer

How to input realtime data from google sheets into urlfetch google scripts?

Based on your title I hope to ...READ MORE

Oct 12, 2018 in Blockchain by Perry
 • 17,100 points • 1,896 views
0 votes
1 answer

Web-scraping from Coinbase with Python (Pycharm)

Data that you want to scrape is ...READ MORE

Sep 4, 2018 in Blockchain by digger
 • 26,740 points • 3,544 views
0 votes
1 answer

Hyperledger Fabric: ./byfn.sh -m up failed

Try adding GODEBUG=netdns=go to the environment variables ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,277 views
0 votes
1 answer

Ethereum Advance token sample

Using > instead of >= is a ...READ MORE

Nov 2, 2018 in Blockchain by Christine
 • 15,750 points • 962 views
0 votes
1 answer

How to install v1.7.3. of Geth using ppa?

The Ethereum PPA generally provides the latest ...READ MORE

Oct 17, 2018 in Blockchain by Christine
 • 15,750 points • 1,644 views
0 votes
1 answer

Blockchain: Installing an earlier version of ethereum using apt-get on

geth does not make the previous version available ...READ MORE

Oct 10, 2018 in Blockchain by Omkar
 • 69,180 points • 1,941 views
0 votes
1 answer

Hyperledger Fabric : How to initialise a 2D array in .cto file?

You could try something like this, with ...READ MORE

Oct 30, 2018 in Blockchain by Omkar
 • 69,180 points • 1,070 views
0 votes
1 answer

Hyperledger Composer cant find business card.

I changed the code to: var businessNetwork = ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,238 views
0 votes
2 answers

Web socket API session automatically disconnecting

Yes, the code given by Christine works! ...READ MORE

Aug 29, 2018 in Blockchain by digger
 • 26,740 points • 3,716 views
0 votes
1 answer

Hyperledger Composer: Error trying to instantiate composer runtime.

It looks like a problem with composer-cli.  A ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,209 views
0 votes
1 answer

Cant query in Hyperledger Composer

There's a mistake in your WHERE statement. ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,175 views
0 votes
1 answer

Why do the resultant hash after mining has a leading no. of zeroes in Blockchain verification?

This is chosen by the DIFFICULTY EQUATION. In ...READ MORE

Aug 10, 2018 in Blockchain by Christine
 • 15,750 points • 4,483 views
0 votes
1 answer

Integrating web3 in cloud functions module

I had this issue and my problem ...READ MORE

Oct 17, 2018 in Blockchain by Perry
 • 17,100 points • 1,530 views
0 votes
1 answer

Hyperledger fabric: vagrant up in devenv fails

This is a problem with vagrant 1.9.3: You ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 1,003 views
0 votes
1 answer

How to read the ETH value and other token values from an account?

You can do this eth.accounts shows you all known ...READ MORE

Oct 22, 2018 in Blockchain by Omkar
 • 69,180 points • 1,286 views
0 votes
1 answer

Unable to change a state variable in a contract

I am assuming that the issue is ...READ MORE

Oct 30, 2018 in Blockchain by Christine
 • 15,750 points • 948 views
0 votes
1 answer

Error when trying to deploy Ethereum smart contract using web3j

Create a new credential based on the Credentials.create ...READ MORE

Oct 3, 2018 in Blockchain by slayer
 • 29,370 points • 2,085 views
0 votes
1 answer

Are there null like thing in solidity

You could create none variable to use it as ...READ MORE

Sep 21, 2018 in Blockchain by digger
 • 26,740 points • 2,600 views
0 votes
1 answer

Is the msg.sender address changed while passing to another contract as a parameter?

I tried your contracts in Remix, but ...READ MORE

Oct 10, 2018 in Blockchain by Omkar
 • 69,180 points • 1,778 views
0 votes
1 answer

re hyperledger's node/sdk: there is no typing definition( index.d.ts )

Looks like a bug in that the ...READ MORE

Oct 23, 2018 in Blockchain by Perry
 • 17,100 points • 1,206 views
0 votes
1 answer

Nodejs cannot access Hyperledger composer shows error

1) you need Node 8.9.x or higher ...READ MORE

Oct 23, 2018 in Blockchain by Perry
 • 17,100 points • 1,170 views
+1 vote
1 answer

Using bccsp instance from chaincode

You can take a look at this code snippet. ...READ MORE

Oct 22, 2018 in Blockchain by Christine
 • 15,750 points • 1,177 views
0 votes
1 answer

How to Query hdfs with Spark Sql

Yyou can achieve this by creating Dataframe. val ...READ MORE

Sep 20, 2018 in Blockchain by slayer
 • 29,370 points • 2,596 views
0 votes
1 answer

Go ethereum: Gradle sync error

Try the below code : maven { ...READ MORE

Oct 24, 2018 in Blockchain by Omkar
 • 69,180 points • 1,124 views
0 votes
1 answer

Bitcoin: parsing Blockchain API using JSON

Because you only add one address to ...READ MORE

Aug 22, 2018 in Blockchain by digger
 • 26,740 points • 3,838 views
0 votes
1 answer

Cant extract hyperledger artifacts

Simplify the PATH first. In a CMD, type: set PATH=C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\ set ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 881 views
0 votes
1 answer

Test ethereum Event Logs with truffle

You are passing tx hash into done() ...READ MORE

Sep 21, 2018 in Blockchain by slayer
 • 29,370 points • 2,504 views
0 votes
3 answers

UnhandledPromiseRejectionWarning: Error: The contract code couldn't be stored, please check your gas limit

I believe bytecode is being treated as ...READ MORE

Sep 24, 2018 in Blockchain by Teja
 • 2,291 views
0 votes
1 answer

How to efficiently hash (SHA 256) in golang data where only the last few bytes changes

You can try the following examples on ...READ MORE

Jun 27, 2018 in Blockchain by aryya
 • 7,460 points • 6,203 views
0 votes
2 answers

How to check if bitcoin address is valid?

For Java, have a look at the ...READ MORE

Aug 20, 2018 in Blockchain by Omkar
 • 69,180 points • 3,835 views
0 votes
1 answer

Docker on mac error message can't connect to Docker endpoint

While CORE_VM_ENDPOINT set to unix:///var/run/docker.sock, please make ...READ MORE

Sep 19, 2018 in Blockchain by slayer
 • 29,370 points • 2,561 views
0 votes
1 answer

How can I deploy a hyperledger business network using docker-compose?

If you want to use Composer, be ...READ MORE

Oct 4, 2018 in Blockchain by Perry
 • 17,100 points • 1,895 views
0 votes
1 answer

pubToAddress method from ethereumjs-util throws AssertionError: false == true

This code works fine: var keythereum = require('keythereum'); var ...READ MORE

Oct 8, 2018 in Blockchain by Omkar
 • 69,180 points • 1,704 views
0 votes
1 answer

truffle migrate Error

testrpc Check your truffle.js config port and ip ...READ MORE

Oct 8, 2018 in Blockchain by Omkar
 • 69,180 points • 1,690 views
0 votes
1 answer

How do I send ether from an EOA to a smart contract?

You include ether to send in the ...READ MORE

Sep 27, 2018 in Blockchain by digger
 • 26,740 points • 2,162 views
0 votes
1 answer

Historical ethereum prices - Coinbase API

def get_spot_price(self, **params): """https://developers.coinbase.com/api/v2#get-spot-price""" ...READ MORE

Sep 21, 2018 in Blockchain by digger
 • 26,740 points • 2,400 views
0 votes
1 answer

How to define the path to hyperledger-fabric chaincode?

You can find that in docker-compose files ...READ MORE

Oct 4, 2018 in Blockchain by Perry
 • 17,100 points • 1,828 views
0 votes
1 answer

Is it possible to send eth to a contract through its constructor from another contract?

I found the solution for this: pragma solidity ...READ MORE

Sep 26, 2018 in Blockchain by slayer
 • 29,370 points • 2,168 views
+1 vote
3 answers

Pass all .dat files in folder to function

os.listdir(path) return names, not fullpaths change parseBlockFile(file) to fullpath = os.path.join(path,file) if os.path.isfile(fullpath) ...READ MORE

Sep 5, 2018 in Blockchain by Saygum
 • 2,972 views
0 votes
1 answer

Mining in private net: Balance not increasing

Use this command to start miner: miner.start() To stop ...READ MORE

Oct 24, 2018 in Blockchain by Omkar
 • 69,180 points • 951 views
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