the CustomGenesis.json have some problem

[leweihe]

in page test-networks.html the CustomGenesis.json
{
"nonce": "0x0000000000000042", "timestamp": "0x0",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"extraData": "0x0", "gasLimit": "0x8000000", "difficulty": "0x400",
"mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"coinbase": "0x3333333333333333333333333333333333333333", "alloc": { }
}
throws exception Fatal: invalid genesis file: json: cannot unmarshal hex string of odd length into Go struct field Genesis.extraData of type hexutil.Bytes

I change the "timestamp": "0x0", "extraData": "0x0" to "extraData": "0x00" "timestamp": "0x00", then it works.

[pirapira]

Can you file a pull-request, applying the change?

[tommystanton]

Making the changes as described by @leweihe did fix the same issue that I had on my machine, but upon further investigation, the current documentation (particularly the change to the documentation in commit ebe69e4) has a CustomGenesis.json example that works just fine.

It seems that it's only extraData that needs to be 0x00 (instead of 0x0). That was fixed in commit 7f5a193.

In conclusion, the documentation online simply needs to be republished (I now realize that there is a wiki on the 'ethereum' GitHub account that is preferred over ethdocs.org).

[tommystanton]

This issue also seems to be related to ethereum/go-ethereum#14356.