Bitcoin Core, the primary software powering approximately 80% of all BTC nodes, has released its long-awaited v30.0 update.
This update, published on October 11, brings optional encrypted node connections, performance and pricing optimizations, and several bug fixes.
But the changes to OP_RETURN, Bitcoin’s built-in “data graffiti wall,” caused the biggest reaction.
What changed in OP_RETURN?
OP_RETURN allows users to attach metadata such as text, images, and digital signatures to Bitcoin transactions without affecting currency functionality. Previously, each OP_RETURN output could carry up to 80 bytes of data, limiting non-financial use cases.
The new release expands that limit to 100,000 bytes, allowing multiple OP_RETURN outputs to be relayed and mined per transaction by default.
In practice, this means that node operators running v30 can process transactions that embed larger or more complex data structures, from NFT-style inscriptions to application metadata, without manual configuration.
The developers explain that this change will enable richer on-chain experimentation. As one market analyst argued:
“OP_RETURN is made to be used. Imagine the power of an uncensorable, unalterable registry. Winners cannot rewrite history. Humanity can carve facts from its own perspective at that very moment. (This is) a treasure trove for future historians and an incredible leap forward for humanity.”
However, some warn that blockchain bloat and pricing pressure could accelerate if users flood the memory pool with data files that are too large.
According to data from Mempool Research, inscription and OP_RETURN transactions already account for 40% of all Bitcoin transactions by volume, 10% by fee, and 28% by weight.
Considering this, widespread adoption of these data-rich transactions could push Bitcoin’s average block size beyond its current 1.5 MB and up to 4 MB per block, which could reshape the network’s economics.
Dividing the community: Utility or spam?
This change sparked a heated debate between Bitcoin developers and node operators.
Some see this as a natural evolution of Bitcoin becoming on par with smart contract-enabled chains like Ethereum. Some argue that it risks diluting Bitcoin’s core role as a peer-to-peer financial network.
Prominent developer Luke Dashjr criticized the change, saying Core 30 “broke” data carrier size controls and made them completely deprecated, allowing for even more “spam output” per transaction.
According to him:
“Bitcoin does not support data storage associated with financial transactions (within OP_RETURN) up to 80 bytes (but not significant), or more than 95 bytes per block in Coinbase. This is not large enough for CSAM. Similar to Inscriptions, exploiting the vulnerability is not a supported behavior/use case, it is just an abuse of a script opcode. You are not storing the data itself, you are just damaging Bitcoin.” garbage script. Expanding OP_RETURN increases the size of supported data storage, making it large enough to include CSAM.
With this in mind, he described v30 as “malware” and urged a “mass migration to Knots,” an alternative client that enforces stricter policies.
However, Blockstream CEO Adam Back countered that denigrating the OP_RETURN change was tantamount to “attacking Bitcoin.”
According to Back, the update includes legitimate security and robustness fixes from “some of the most accomplished developers on the planet.”
What’s next?
Amid the growing rift, some community members are proposing policy-level compromises regarding the update.
Renowned cryptologist Nick Szabo suggested:
“Going forward, we will be deprecating the use of OP_RETURN in financial transaction functionality. We will be adding the ability to keep old OP_RETURNs while removing new ones.”
Meanwhile, BitMEX Research highlighted the concept of OP_Return2, a soft fork mechanism that allows transactions to commit to hashes of up to 8 MB of external data without forcing full nodes to verify or store it.
According to the company, this proposal has the potential to reduce on-chain bloat while maintaining data integrity.
But the researchers caution that miners may have little incentive to include such transactions if the additional complexity cannot be offset by fees. We also note that similar timestamping functionality already exists at low cost.
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