Bitcoin Core v30 Sparks Debate Over OP_RETURN Data Expansion

The Bitcoin Core v30.0 update, published on October 11, represents the most significant evolution of Bitcoin’s data capabilities in years. The software, which powers approximately 80% of all BTC nodes, has fundamentally altered how OP_RETURN functions within the Bitcoin ecosystem. Previously constrained to just 80 bytes per transaction, OP_RETURN now supports up to 100,000 bytes and allows multiple data outputs per transaction to be relayed and mined by default.

This technical shift transforms Bitcoin’s built-in ‘data graffiti wall’ from a limited annotation tool into a substantial data storage mechanism. Node operators running v30 can now process transactions embedding larger or more complex data structures without manual configuration, enabling applications ranging from NFT-style inscriptions to comprehensive application metadata. The change effectively gives developers 1,250 times more data capacity than previously available, opening new possibilities for on-chain experimentation and data permanence.

According to Mempool Research data, the demand for such data-heavy transactions already exists at scale. Inscriptions and OP_RETURN transactions currently account for 40% of all Bitcoin transactions by count, 10% by fees, and 28% by weight. This existing usage pattern suggests the expanded capacity could see immediate adoption, potentially reshaping how Bitcoin’s blockchain is utilized beyond pure financial transactions.

The OP_RETURN expansion has exposed a fundamental philosophical rift within the Bitcoin development community. Supporters view the change as a natural evolution that brings Bitcoin closer to parity with smart-contract-capable chains like Ethereum. One market analyst captured the optimistic perspective, describing OP_RETURN as ‘a gold mine for future historians and an incredible leap for humanity’ that creates ‘an uncensorable, unmodifiable registry’ where ‘victors can’t rewrite history.’

However, prominent developer Luke Dashjr has emerged as the update’s most vocal critic, labeling Bitcoin Core v30 as ‘malware’ that ‘broke’ the datacarrier size control. According to Dashjr, Bitcoin was never designed to support data storage beyond minimal attachments to financial transactions. He argues that expanding OP_RETURN to 100,000 bytes creates risks beyond simple blockchain bloat, potentially enabling harmful content storage while fundamentally altering Bitcoin’s core purpose as a peer-to-peer financial network.

Blockstream CEO Adam Back has countered these criticisms, defending the update as containing legitimate security and robustness fixes from ‘some of the most skilled developers on the planet.’ Back characterizes opposition to the OP_RETURN changes as ‘attacking Bitcoin’ itself, highlighting the deep ideological divisions the update has exposed within the development community. This split has prompted Dashjr to urge a ‘mass migration to Knots,’ an alternative Bitcoin client that enforces stricter data policies.

The practical implications of expanded OP_RETURN capacity extend beyond philosophical debates to tangible network economics. With inscriptions already representing 40% of transaction volume, wider adoption of data-heavy transactions could push Bitcoin’s average block size beyond its current 1.5 MB to as high as 4 MB per block. Such a jump would represent a fundamental shift in Bitcoin’s block space economics, potentially increasing fee pressure and accelerating what critics describe as ‘blockchain bloat.’

Amid the controversy, community members have proposed technical compromises. Renowned cryptographer Nick Szabo suggested deprecating OP_RETURN for financial transaction functionality while maintaining backward compatibility. Meanwhile, BitMEX Research has highlighted the concept of OP_Return2, a soft-fork mechanism that would allow transactions to commit to hashes of up to 8 MB of external data without forcing full nodes to validate or store the actual content.

However, researchers caution that miners might have little incentive to include such transactions if fees don’t offset the extra complexity. They also note that similar timestamping functions already exist at lower cost, raising questions about whether the expanded OP_RETURN capacity addresses a genuine need or simply creates new problems. As the Bitcoin community grapples with these questions, the v30 update represents a pivotal moment in determining whether Bitcoin will remain primarily a financial network or evolve into a more versatile data layer.