Bitcoin Core drops OP_RETURN deprecation hours before v30 release

Bitcoin Core developers reversed their plan to deprecate the user configurability of OP_RETURN’s default datacarriersize just hours before the scheduled release of Core version 30 (v30), one of the most controversial and widely publicized changes to Bitcoin’s dominant software for thousands of node operators.

Pull request (PR) 33453 was merged by Core maintainer Ava Chow into Bitcoin Core’s master branch via GitHub yesterday evening New York time.

The eleventh-hour accommodation signaled a slight victory for a dissident movement led by Knots node operators who have vocally protested Core’s easements of OP_RETURN’s datacarriersize.

In the view of many Knots node operators, most nodes’ memory pools (mempools) should reject transactions by default carrying large amounts of data unrelated to the on-chain movement of bitcoin (BTC).

Rather than burden node operators with storing and relaying arbitrary data around the network for non-currency uses of BTC, defaults should deter such arbitrary data storage in OP_RETURN outputs.

Read more: Knots leader says Bitcoin Core v30 could host illegal adult content

Although Core v30 software will still increase OP_RETURN’s datacarriersize from less than 90 bytes to 100KB for its default mempool, v30 will retain and not plan to deprecate the ability for users to manually modify that cap on the quantity of arbitrary data that OP_RETURN outputs will carry.

Deprecation of datacarrier and datacarriersize configuration options was originally planned for release this October in Core v30.

However, due to the successful review and merge of PR 33453, deprecation of user configurability is now on hold indefinitely.

The last-minute policy reversal doesn’t undo all of the controversial changes from v29 going into v30.