Bitcoin Core to remove OP-Return limit unilaterally

A unilateral decision by Bitcoin Core will scrap the controversial OP-Return limit.

The OP_RETURN controversy is intensifying, with Bitcoin Core developers—the creators of the most widely used node software—announcing plans to remove the feature in the next release.

With the change, the limit on adding arbitrary data to Bitcoin transactions will no longer apply.

“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,” read the announcement on GitHub by Bitcoin developer Greg Sanders on May 5.

The long-standing limit was originally a “gentle signal that block space should be used sparingly for non-payment proof of publication data,” has outlived its utility, he added.

Peter Todd, an early Bitcoin innovator, submitted proposal PR 32359 at the request of Chaincode Labs.

OP_RETURN is a script opcode that people can use to write arbitrary data on the blockchain and also mark a transaction output as invalid.

Unlike typical transaction outputs, OP_RETURN outputs cannot be used for spending and don’t impact the number of unspent transaction outputs (UTXOs).

According to Sanders, the initial limit no longer serves its purpose, with people exploiting methods like fake output addresses that worsen the network and some mining services disregarding the restriction.

“Large-data inscriptions are happening regardless and can be done in more or less abusive ways; the cap merely channels them into more opaque forms that cause damage to the network.”

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Removing the limit, he argues, “yields at least two tangible benefits: a cleaner UTXO set and more consistent default behavior.”

Three options were evaluated: keeping the cap, raising it, or removing it. They decided to eliminate the cap, which garnered “broad, though not perhaps unanimous, support.”

“Many users find this to be an undesirable change for a number of reasons,” said Bitcoiner Samson Mow on X on May 5.

He added that users “can refuse to upgrade and stay on 29.0 or run another implementation” of the network.

Critics argued that the proposal lacked proper consensus and voiced concerns about Bitcoin’s financial utility being downshifted. They also pointed out the possibility of undisclosed conflicts of interest.

“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.