coinbaseaux flags is empty and coinbasetx is missing #12335

When I request getblocktemplate, coinbaseaux flags is empty. Also coinbasetx is not included which I understand need to be calculated. Where is complete example of how to create that one ? Wiki example just assums conbasetx in included in response which is not. I want to create coinbase with all rewards going to single wallet address.

{
            "capabilities": ["proposal"],
            "version": 536870912,
            "rules": ["csv",
            "segwit"],
            "vbavailable": {

            },
            "vbrequired": 0,
            "previousblockhash": "00000000000000000011f84134ea90036cf16260ef1e2532af2ad4c4128833fa",
            "transactions": [],
            "coinbaseaux": {
                "flags": ""
            },
            "coinbasevalue": 1390108740,
            "longpollid": "00000000000000000011f84134ea90036cf16260ef1e2532af2ad4c4128833fa6254",
            "target": "0000000000000000006c21460000000000000000000000000000000000000000",
            "mintime": 1517434058,
            "mutable": ["time",
            "transactions",
            "prevblock"],
            "noncerange": "00000000ffffffff",
            "sigoplimit": 80000,
            "sizelimit": 4000000,
            "weightlimit": 4000000,
            "curtime": 1517440540,
            "bits": "176c2146",
            "height": 507012,
            "default_witness_commitment": "6a24aa21a9ed63d9ce8e02cbe0c044825f7448ebd2819c3af1390057183bee668219e159be2a"
    }

@luke-jr

Is this still an issue with a recent version of Bitcoin Core? If yes, what are the steps to reproduce?

Hi,

I have installed Bitcoin Core version v0.21.0 and it is still an issue. You can reproduce just executing bitcoin-cli getblocktemplate '{"rules": ["segwit"]}'

@fcojperez coinbaseaux/coinbasetx are not required at all; see BIPs 22 & 23 for the spec and libblkmaker for an example client.

Hi @luke-jr

Thanks for the feedback, your comment helped to understand a possible bug in code that is consuming getblocktemplate JSON

Cheers P

@luke-jr The RPC documentation says the coinbase transaction scriptSig should contain the coinbaseaux values.

If getblocktemplate returned a value for coinbaseaux, would it be required? If not, why is coinbaseaux included in the response?

The issue is still happening with the latest version, but the value is now an empty object.

"coinbaseaux": { }

Here's a video of the Bitcoin CLI response.

https://www.tiktok.com/@ghostcompute/video/7051706476691442990?sender_device=mobile&sender_web_id=7042509351429473798&is_from_webapp=v1&is_copy_url=0

If getblocktemplate returned a value for coinbaseaux, would it be required?

It is undefined what behaviour to expect if coinbaseaux is ignored, but the spec says any values provided SHOULD be included in the scriptSig.

The issue is still happening with the latest version, but the value is now an empty object.

It's supposed to be empty (in recent versions).

Is there recent documentation for creating coinbase transactions in recent versions, or should I just read the source code?

BIPs 22, 23, and the amendment for versionbits should be everything IIRC

Nothing has changed in regard to coinbaseaux though

Ok I'll circle back to this if there's an invalid coinbase error during block submission.

I am going to lock the conversation on this issue from 2018 (4 years ago). Please open a new thread for any new issues.