#### 2013, OP_RETURN made standard: - [RFC: empty scriptPubKeys and OP_RETURN for marking unspendable txouts by petertodd](https://gnusha.org/pi/bitcoindev/20130212151108.GA639@savin/) - [PR 2738 by jgarzik](https://github.com/bitcoin/bitcoin/pull/2738) - [v0.9.0 release notes](https://bitcoin.org/en/release/v0.9.0#opreturn-and-data-in-the-block-chain) #### 2014, OP_RETURN default increased to 80 bytes: - [mailing list request by flavien](https://gnusha.org/pi/bitcoindev/CABbpET9eTgk1GyxYbcG++O_rqsnfB7w5_Xp4XgE6qwkmGsm1eg@mail.gmail.com/) - [PR 5286 by flavien](https://github.com/bitcoin/bitcoin/pull/5286) - [commit a930658 by flavien](https://github.com/bitcoin/bitcoin/commit/a9306587a42eac7fb889b9c8d03140980fdf1398) #### 2016, OP_RETURN used for Segwit (witness root hash in coinbase tx): - [preparing for segwit, bitcointalk](https://bitcointalk.org/index.php?topic=1674590.0) - [BIP141: commitment structure](https://en.bitcoin.it/wiki/BIP_0141#Commitment_structure) #### 2023, Remove OP_RETURN restrictions: - [PR 28130 by petertodd, requested by christopherA](https://github.com/bitcoin/bitcoin/pull/28130) - [email thread](https://gnusha.org/pi/bitcoindev/CACrqygD8ZF-PqKuFK7-SgiPdZQ9ewt+9QGXytpf8+NYjjNjyfA@mail.gmail.com/) - [petertodd's libre relay requested by lightcoin](https://x.com/lightcoin/status/1733257392668766494) #### 2025, Remove OP_RETURN restrictions: - [Dev mailing list thread started by darosior](https://groups.google.com/g/bitcoindev/c/d6ZO7gXGYbQ) - [PR 32359 by petertodd, requested by darosior](https://github.com/bitcoin/bitcoin/pull/32359) - [PR 32381 by darosior](https://github.com/bitcoin/bitcoin/pull/32381) - [PR 32406 by instagibbs](https://github.com/bitcoin/bitcoin/pull/32406) - [Explanation by instagibbs](https://gist.github.com/instagibbs/c436110890ab25aa9997b13c2270d5ce) - [Wuille's public-relations message](https://gist.github.com/sipa/2521731e65ba779e3ce9f9305c6a538c) - [Wuille's public-relations bitcoincore PR](https://github.com/bitcoin-core/bitcoincore.org/pull/1139) - [Wuille's public-relations statement on bitcoincore.org](https://bitcoincore.org/en/2025/06/06/relay-statement/) ---- ### Some of the earliest bitcointalk mentions of op_return: - Sep 2010: ["I added some information on the "OP_RETURN" bug that triggered the 0.3.5 release" - gavin](https://bitcointalk.org/index.php?topic=1045.msg12908#msg12908) - Jan 2012: ["ArtForz discovered a bug in July of 2010 (the OP_RETURN bug) that allowed anybody to spend anybody else's bitcoins. It by far Bitcoin's biggest bug and Satoshi's biggest brain-fart." - gavin](https://bitcointalk.org/index.php?topic=58579.msg691432#msg691432) - Mar 2013: ["I'd encourage you to start a discussion about making OP_RETURN, possibly followed by a small amount of data" - petertodd](https://bitcointalk.org/index.php?topic=157141.msg1665977#msg1665977) - Sep 2013: ["Here I assume zero value OP_RETURN outputs are standard" - jl2012](https://bitcointalk.org/index.php?topic=286178.0) - Dec 2013: ["I have an idea that uses OP_RETURN" - locksley](https://bitcointalk.org/index.php?topic=391491.0)