Bitcoin Core to Remove OP_RETURN Limit in Next Upgrade

Bitcoin Core developers have confirmed that the next software release will lift the long-standing 80-byte restriction on OP_RETURN transaction outputs.

The decision was met with concern in the crypto space as users expressed dissatisfaction with the move.

OP_RETURN Has Outlived Its Purpose

The information was relayed in a May 5 GitHub announcement by Bitcoin developer Gregory Sanders, which read:

“Bitcoin Core’s next release will, by default, relay and mine transactions whose OP_RETURN outputs exceed 80 bytes and allow any number of these outputs.”

Sanders explained that the 80-byte limit was originally a “gentle signal that block space should be used sparingly for non-payment proof of publication data,” but that it has now outlived its usefulness.

OP_RETURN is a type of Bitcoin transaction output that allows small amounts of data to be stored on the blockchain. Unlike regular outputs, they are unspendable and therefore don’t contribute to unspent transaction outputs (UTXOs).

Developers noted that many private mining accelerators already ignore the limit, and users often find workarounds. Instead of stopping misuse, they have started embedding data in more complex ways, such as crafting fake output public keys or using spendable scripts to hide data. This makes the network harder to manage and less efficient.

Some proposed introducing blacklists to stop these tricks, but the developers rejected that idea. They argued that blacklists are unreliable, hard to maintain, and could even lead to innocent people losing funds.

Sanders also clarified that removing the restriction doesn’t weaken Bitcoin’s security. Rules like the 4 million weight unit block limit and other safeguards remain in place. However, the change brings some improvements, such as a cleaner UTXO set and more consistent behavior across the network.

He explained that developers considered three options before reaching a decision: keeping the cap, raising it, or removing it entirely. According to him, the third option received “broad, though not unanimous support.”

Community Debate

The announcement has started a debate in the crypto community. Bitcoin Knots maintainer Luke Dashjr described the removal as “utter insanity.” Bitcoiner Samson Mow said on X on May 5 that users “can refuse to upgrade and stay on 29.0 or run another implementation,” referring to Knots.

Critics also argued that the proposal was introduced without a proper decision-making process. “I think one thing is pretty clear: there is no consensus at the moment on this OP_RETURN issue,” said Ten31 Fund managing partner Marty Bent.

Meanwhile, Sanders has defended the removal of the cap as aligned with Bitcoin’s ethos of  “minimal and transparent rules.”

Despite these assurances, the community still doesn’t agree. “This marks a fundamental shift in the direction of Bitcoin,” one commenter warned on GitHub. “This is the largest mistake Core can make at this juncture,” another added.