[Ethereum] Fatal:invalid genesis file:hex string has length 2, want 64 for common.hash

blockchaingenesis

I'm new on the website. I'm following a french tutorial (yes i'm french) to create my own blockchain network. After installing all Geth stuff, creating my genesis file as following :

{
"nonce": "0x00",
"difficulty": "0x1000",
"mixHash": "0x00",
"timestamp": "0x00",
"parentHash": "0x00",
"extraData": "0x00",
"gasLimit": "0x1000000000"
}

Then I tiped the following line :

sudo geth –datadir ./noeud1 –networkid "100" init genesis.json

I have the following error :

Fatal:invalid genesis file: hex string has length 2, want 64 for common.hash

Thank you for helping 🙂

Best Answer

Copy the follwing code in your genesis.json file

{
 "nonce": "0x0000000000000042",
 "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
 "difficulty": "0x400",
 "alloc": {},
 "coinbase": "0x0000000000000000000000000000000000000000",
 "timestamp": "0x00",
 "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
 "extraData": "0x",
 "gasLimit": "0xffffffff",
 "config": {
    "chainId": 59,
    "homesteadBlock": 0,
    "eip155Block": 0,
    "eip158Block": 0
 }
}

You can put your own chainid , not 1,2,3 they are Reserved

then run the command

geth --datadir ~ / yourDataDirectory  init genesis.json

or Follow this tutorial, its very helpful. Chainskills

Related Solutions

Go-Ethereum Error – Fixing ‘Max Invalid Genesis File: Hex String Has Odd Length’ Error

The same problem happened to me with geth 1.6, with a genesis file similar to yours.

Last friday geth updated to 1.6 (https://github.com/ethereum/go-ethereum/releases/tag/v1.6.0).

In this release:

Genesis block JSON handling is stricter and safer. Notably, most JSON fields now require the "0x" prefix. (#3794)

I found this documentation page: https://github.com/ethereum/go-ethereum/wiki/Private-network

In this page there is an example of a genesis file that works on geth 1.6.

I think your genesis file works with previous versions.

[Ethereum] How to generate the correct go-ethereum bootnode when creating a private blockchain

If you can't telnet then there is something wrong with your networking. Either your virtual network connection between hosts is the problem or there is a firewall blocking connections.

If you are just getting started then I'd keep things really simple first of all and:

Use standard geth nodes
Run your nodes on one virtual machine on different ports

e.g. initialise your geth nodes like this:

ethuser@host01:~$ mkdir test1
ethuser@host01:~$ cd test1
ethuser@host01:~/test1$ mkdir nodeA
ethuser@host01:~/test1$ mkdir nodeB
ethuser@host01:~/test1$ <use your favourite editor to create a genesis.json file in this directory>
ethuser@host01:~/test1$ geth --datadir nodeA init genesis.json
WARN [08-04|10:41:41] No etherbase set and no accounts found as default 
INFO [08-04|10:41:41] Allocated cache and file handles         database=/home/ethuser/test1/nodeA/geth/chaindata cache=16 handles=16
INFO [08-04|10:41:41] Writing custom genesis block 
INFO [08-04|10:41:41] Successfully wrote genesis state         database=chaindata                                hash=dd3f8d…707d0d
INFO [08-04|10:41:41] Allocated cache and file handles         database=/home/ethuser/test1/nodeA/geth/lightchaindata cache=16 handles=16
INFO [08-04|10:41:41] Writing custom genesis block 
INFO [08-04|10:41:41] Successfully wrote genesis state         database=lightchaindata                                hash=dd3f8d…707d0d
ethuser@host01:~/test1$ geth --datadir nodeB init genesis.json
WARN [08-04|10:41:52] No etherbase set and no accounts found as default 
INFO [08-04|10:41:52] Allocated cache and file handles         database=/home/ethuser/test1/nodeB/geth/chaindata cache=16 handles=16
INFO [08-04|10:41:52] Writing custom genesis block 
INFO [08-04|10:41:52] Successfully wrote genesis state         database=chaindata                                hash=dd3f8d…707d0d
INFO [08-04|10:41:52] Allocated cache and file handles         database=/home/ethuser/test1/nodeB/geth/lightchaindata cache=16 handles=16
INFO [08-04|10:41:52] Writing custom genesis block 
INFO [08-04|10:41:52] Successfully wrote genesis state         database=lightchaindata                                hash=dd3f8d…707d0d
ethuser@host01:~/test1$

Then launch your first geth node like this

ethuser@host01:~/test1$ geth --datadir nodeA --networkid 1234567 console
WARN [08-04|10:42:22] No etherbase set and no accounts found as default 
INFO [08-04|10:42:22] Starting peer-to-peer node               instance=Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1
INFO [08-04|10:42:22] Allocated cache and file handles         database=/home/ethuser/test1/nodeA/geth/chaindata cache=128 handles=1024
WARN [08-04|10:42:22] Upgrading chain database to use sequential keys 
INFO [08-04|10:42:22] Initialised chain configuration          config="{ChainID: 1907 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: 0 EIP158: 0 Metropolis: <nil> Engine: unknown}"
INFO [08-04|10:42:22] Disk storage enabled for ethash caches   dir=/home/ethuser/test1/nodeA/geth/ethash count=3
INFO [08-04|10:42:22] Disk storage enabled for ethash DAGs     dir=/home/ethuser/.ethash                 count=2
WARN [08-04|10:42:22] Upgrading db log bloom bins 
INFO [08-04|10:42:22] Bloom-bin upgrade completed              elapsed=252.683µs
INFO [08-04|10:42:22] Initialising Ethereum protocol           versions="[63 62]" network=1234567
INFO [08-04|10:42:22] Database conversion successful 
INFO [08-04|10:42:22] Loaded most recent local header          number=0 hash=dd3f8d…707d0d td=40
INFO [08-04|10:42:22] Loaded most recent local full block      number=0 hash=dd3f8d…707d0d td=40
INFO [08-04|10:42:22] Loaded most recent local fast block      number=0 hash=dd3f8d…707d0d td=40
INFO [08-04|10:42:22] Starting P2P networking 
INFO [08-04|10:42:22] UDP listener up                          self=enode://9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817@[::]:30303
INFO [08-04|10:42:22] RLPx listener up                         self=enode://9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817@[::]:30303
INFO [08-04|10:42:22] IPC endpoint opened: /home/ethuser/test1/nodeA/geth.ipc 
Welcome to the Geth JavaScript console!

instance: Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1
 modules: admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

>

And then start up your second node. In my case I needed to use ethuser@host01:~/test1$ geth --datadir nodeB --port 30304 --networkid 1234567 --bootnodes enode://9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817@127.0.0.1:30303

Wait a few moments to give the nodes a chance to connect and then double check in your console that admin.peers returns some more info, e.g.

> admin.peers
[{
    caps: ["eth/63"],
    id: "9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817",
    name: "Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1",
    network: {
      localAddress: "127.0.0.1:41900",
      remoteAddress: "127.0.0.1:30303"
    },
    protocols: {
      eth: {
        difficulty: 40,
        head: "0xdd3f8d61f38ebc195a6c9b0e5888e7e035f31ecd92e4427fb01176b984707d0d",
        version: 63
      }
    }
}]
>

I've left out creating accounts etc as you don't specifically ask it but if you're interested here are some more of my own newbie experiences: https://alanbuxton.wordpress.com/2017/07/19/first-steps-with-ethereum-private-networks-and-smart-contracts-on-ubuntu-16-04/

Best Answer

Related Solutions

Go-Ethereum Error – Fixing ‘Max Invalid Genesis File: Hex String Has Odd Length’ Error

[Ethereum] How to generate the correct go-ethereum bootnode when creating a private blockchain

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