Bitcoin Core 30.0 Boosts OP_RETURN Limit for More Data

The latest release of Bitcoin Core, version 30.0, introduces significant technical adjustments to the network, most notably an increase in the OP_RETURN data limit. This change, long debated within the cryptocurrency community, aims to enhance the network’s capacity for non-financial data, potentially impacting the evolution of various Bitcoin-based applications and protocols.

This foundational update, released by the developers responsible for maintaining and advancing the Bitcoin network, brings forth a suite of modifications designed to bolster both the security and throughput of the blockchain. The Bitcoin Core project, operating as an open-source initiative, relies on community contributions and a dedicated development team to ensure the stable operation of its “reference client.”

Key Enhancements in Bitcoin Core v30.0

The v30.0 update incorporates several notable features, including:

• A revised limit of 2,500 for “legacy” signature operations per standard transaction.
• An increased default for the -datacarriersize parameter to 100,000 bytes.
• The allowance of multiple OP_RETURN outputs per transaction, significantly expanding the capacity for embedding non-financial data.
• A redesigned buffer for “orphan” transactions to better defend against Denial of Service (DoS) attacks.
• The introduction of a new bitcoin command for the execution line, designed to streamline the launch of other executables.
• Reinstated support for external signing on the Windows operating system.
• Implementation of a mining IPC interface command to facilitate connections with clients such as Stratum v2.
• An updated coinstatsindex implementation.
• Various adjustments to the Remote Procedure Call (RPC) interface.
• Deprecation of the creation or loading of legacy BDB wallets, with migration to the new format enabled via the migratewallet function.
• A migration from Qt 5 to Qt 6, bringing dark mode support to Windows and the Metal backend to macOS.
• With the release of v30.0, the 27.x branch and earlier versions have reached their End of Life status.

The most consequential aspect of this release is the substantial increase in the OP_RETURN limit. This parameter, previously set at a more restrictive 80 bytes, has been expanded to 100,000 bytes. This modification is anticipated to facilitate a rise in non-financial transactions on the Bitcoin network, potentially supporting the growth of emerging standards like Runes.

Community Reactions and Implications

The decision to increase the OP_RETURN limit has elicited varied responses from prominent figures within the cryptocurrency space. Supporters argue that lifting such restrictions is essential for keeping the network technologically current. Conversely, critics express concerns that this change could transform the base layer of Bitcoin into a platform for experimental applications, potentially introducing data that is not core to its financial function.

Early Bitcoin developer Peter Todd has previously voiced support for such an expansion, suggesting that existing mechanisms already accommodate such data. However, cryptography pioneer Nick Szabo has cautioned against this approach, recommending alternative software like Knots as a more controlled solution. Szabo expressed concern that the increased limit might inadvertently encourage the inclusion of “illegal content” for which archival node operators could face legal repercussions, unless robust mechanisms for content removal are concurrently implemented. The Bitcoin Core v30.0 release, by increasing the OP_RETURN capacity, signals a direction towards greater flexibility in how the blockchain’s foundational layer can be utilized.