On June 9, news emerged that Bitcoin core developers plan to release version 30 of the Bitcoin Core software in October this year. This version will no longer filter OP_RETURN outputs that contain a large amount of non-financial data. This change will increase the default data carrier limit from the current 80 bytes to nearly 4MB, while allowing node operators to manually modify the -datacarrier and -datacarriersize parameters.
Once this news was released, it immediately sparked intense discussions within the Bitcoin community. Proponents of the proposal believe it is a necessary step to unleash the innovative potential of the blockchain, while opponents view it as a betrayal of Bitcoin's core values. The intensity of emotions even led some Bitcoin holders to liquidate their positions.
The OP_RETURN expansion controversy has been ongoing for nearly two years. Although core developers plan to implement the expansion in the Bitcoin Core software update in October, the debate continues and this is not the final outcome.
What is scaling? Why does it cause controversy?
The turmoil began in July 2023.
On July 23, 2023, core developer and a key proponent of scaling, Peter Todd, submitted PR#28130, proposing the removal of the data size limit for OP_RETURN, but it was unsuccessful.
OP_RETURN is an opcode in Bitcoin script used to embed a small amount of data in Bitcoin transactions. It allows users to store data on the blockchain, but these outputs are "provably unspendable," thus not adding to the burden of the UTXO (Unspent Transaction Output) set. The current default limit for OP_RETURN data size in Bitcoin Core is 80 bytes, and propagation of OP_RETURN transactions larger than 83 bytes is limited by node policies (rather than consensus rules).
On April 28, 2025, Peter Todd submitted the same proposal PR#32359，同时instagibbs 提出了一个相对温和的提议 PR#32406 again, suggesting to temporarily retain the configuration option but not to impose restrictions by default. On June 9, Bitcoin Core developer Gloria Zhao posted on GitHub, stating that the Bitcoin Core 30 update planned for release on October 30 will remove the 80-byte limit on the OP_RETURN function, allowing each output to carry up to 4 megabytes of data. Currently, the controversy triggered by this change is still ongoing, with significant differences of opinion within the community regarding this change.
The core assertion of these developers promoting scalability is that the current 80-byte limit hinders the development of key applications. For example, data embedding that complies with the W3C verifiable credential standard requires more than 96 bytes of space, and enhanced lightning network atomic swap metadata as well as complex state proofs of the RGB protocol may also be affected by the 80-byte limit, leading to an inability to fully or efficiently implement the relevant functions.
This news has once again sparked intense debate within the Bitcoin community, with both sides holding their ground, and opponents expressing their protests through actions. For example, on June 11, Jason Hughes, the vice president of mining pool OCEAN, announced that he would sell all his Bitcoin and exit the industry in protest of the recent OP_RETURN change decision.
The expansion dispute that has spread for nearly two years triggers a lot of discussion every time there is a new development, but more of the discussion stems from the differing opinions within the Bitcoin Core development team, as well as the resulting debates among extreme believers in Bitcoin. For example, some developers believe that the risks of slight expansion are controllable and the benefits are obvious; while another faction strongly opposes this, fearing a slide into the abyss of feature inflation. Technical discussions quickly escalate into ideological battles.
Interestingly, mainstream mining pools and exchanges generally do not express their stance on this.
The Core of the Controversy: What is the Ultimate Role of Bitcoin?
Proponents start with Satoshi Nakamoto's original design intentions, arguing that the Satoshi Nakamoto-era Bitcoin protocol does not have any data size limit for OP_RETURN, and that removing the 80-byte limit is a return to the original spirit of Bitcoin, in line with its essence as an open system, and that the technology should remain open and the use of it should be determined by community innovation. The current 80-byte limit can be bypassed by committing miners directly to the mempool (e.g., MARA Slipstream) or unlimited nodes (e.g., Libre Relay), so removing the limit doesn't actually introduce more risk.
On the other hand, scaling up will also reduce the network burden. For example, current protocols like inscriptions store over 80 bytes of data through multiple transactions. After removing the limitations, inscriptions can directly store data via OP_RETURN, reducing unnecessary multiple transactions and thus alleviating pressure on the network.
In addition, after the expansion, it can also increase miners' income. With Bitcoin's halving every four years, miners' income decreases. Allowing large OP_RETURN transactions enables miners to earn more income by competing for block space, incentivizing them to continue investing in computational power and strengthening the security of the Bitcoin network.
The main argument of the opponents is that this move will occupy block space, and removing restrictions may lead to more non-transactional data (such as spam, low-value tokens, etc.) being written onto the chain, occupying block space, which in turn will raise transaction fees and impact the efficiency and practicality of Bitcoin as a value transfer network. Furthermore, this contradicts the original design intention of Bitcoin as a value transfer network, and could turn the blockchain into a data storage platform, keeping images, text, and audio away from the blockchain, maintaining the "purity" of Bitcoin for bookkeeping rather than data storage.
In addition, the removal of configuration options by Bitcoin Core (such as -datacarrier and -datacarriersize) is seen as depriving users of their right to choose, enforcing a "paternalistic" policy, while retaining configuration options aligns more with Satoshi Nakamoto's decentralized philosophy of "one CPU one vote."
The intense debate essentially revolves around the ultimate role of Bitcoin in this world. Is it a pure, immutable "digital gold" and a cornerstone of value storage? Or is it a foundational settlement layer that supports limited but useful applications?
OP_RETURN scaling touches on this fundamental philosophical divide. Opponents argue that any attempt at applicability is a blasphemy of "sacredness"; Proponents argue that moderate evolution is the only way to thrive. Times are changing, public chains are constantly rising, and Bitcoin is once again at the crossroads of choice.
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The controversy over OP_RETURN expansion has resurfaced. What exactly is Bitcoin?
Jessy, Golden Finance
On June 9, news emerged that Bitcoin core developers plan to release version 30 of the Bitcoin Core software in October this year. This version will no longer filter OP_RETURN outputs that contain a large amount of non-financial data. This change will increase the default data carrier limit from the current 80 bytes to nearly 4MB, while allowing node operators to manually modify the -datacarrier and -datacarriersize parameters.
Once this news was released, it immediately sparked intense discussions within the Bitcoin community. Proponents of the proposal believe it is a necessary step to unleash the innovative potential of the blockchain, while opponents view it as a betrayal of Bitcoin's core values. The intensity of emotions even led some Bitcoin holders to liquidate their positions.
The OP_RETURN expansion controversy has been ongoing for nearly two years. Although core developers plan to implement the expansion in the Bitcoin Core software update in October, the debate continues and this is not the final outcome.
What is scaling? Why does it cause controversy?
The turmoil began in July 2023.
On July 23, 2023, core developer and a key proponent of scaling, Peter Todd, submitted PR#28130, proposing the removal of the data size limit for OP_RETURN, but it was unsuccessful.
OP_RETURN is an opcode in Bitcoin script used to embed a small amount of data in Bitcoin transactions. It allows users to store data on the blockchain, but these outputs are "provably unspendable," thus not adding to the burden of the UTXO (Unspent Transaction Output) set. The current default limit for OP_RETURN data size in Bitcoin Core is 80 bytes, and propagation of OP_RETURN transactions larger than 83 bytes is limited by node policies (rather than consensus rules).
On April 28, 2025, Peter Todd submitted the same proposal PR#32359，同时instagibbs 提出了一个相对温和的提议 PR#32406 again, suggesting to temporarily retain the configuration option but not to impose restrictions by default. On June 9, Bitcoin Core developer Gloria Zhao posted on GitHub, stating that the Bitcoin Core 30 update planned for release on October 30 will remove the 80-byte limit on the OP_RETURN function, allowing each output to carry up to 4 megabytes of data. Currently, the controversy triggered by this change is still ongoing, with significant differences of opinion within the community regarding this change.
The core assertion of these developers promoting scalability is that the current 80-byte limit hinders the development of key applications. For example, data embedding that complies with the W3C verifiable credential standard requires more than 96 bytes of space, and enhanced lightning network atomic swap metadata as well as complex state proofs of the RGB protocol may also be affected by the 80-byte limit, leading to an inability to fully or efficiently implement the relevant functions.
This news has once again sparked intense debate within the Bitcoin community, with both sides holding their ground, and opponents expressing their protests through actions. For example, on June 11, Jason Hughes, the vice president of mining pool OCEAN, announced that he would sell all his Bitcoin and exit the industry in protest of the recent OP_RETURN change decision.
The expansion dispute that has spread for nearly two years triggers a lot of discussion every time there is a new development, but more of the discussion stems from the differing opinions within the Bitcoin Core development team, as well as the resulting debates among extreme believers in Bitcoin. For example, some developers believe that the risks of slight expansion are controllable and the benefits are obvious; while another faction strongly opposes this, fearing a slide into the abyss of feature inflation. Technical discussions quickly escalate into ideological battles.
Interestingly, mainstream mining pools and exchanges generally do not express their stance on this.
The Core of the Controversy: What is the Ultimate Role of Bitcoin?
Proponents start with Satoshi Nakamoto's original design intentions, arguing that the Satoshi Nakamoto-era Bitcoin protocol does not have any data size limit for OP_RETURN, and that removing the 80-byte limit is a return to the original spirit of Bitcoin, in line with its essence as an open system, and that the technology should remain open and the use of it should be determined by community innovation. The current 80-byte limit can be bypassed by committing miners directly to the mempool (e.g., MARA Slipstream) or unlimited nodes (e.g., Libre Relay), so removing the limit doesn't actually introduce more risk.
On the other hand, scaling up will also reduce the network burden. For example, current protocols like inscriptions store over 80 bytes of data through multiple transactions. After removing the limitations, inscriptions can directly store data via OP_RETURN, reducing unnecessary multiple transactions and thus alleviating pressure on the network.
In addition, after the expansion, it can also increase miners' income. With Bitcoin's halving every four years, miners' income decreases. Allowing large OP_RETURN transactions enables miners to earn more income by competing for block space, incentivizing them to continue investing in computational power and strengthening the security of the Bitcoin network.
The main argument of the opponents is that this move will occupy block space, and removing restrictions may lead to more non-transactional data (such as spam, low-value tokens, etc.) being written onto the chain, occupying block space, which in turn will raise transaction fees and impact the efficiency and practicality of Bitcoin as a value transfer network. Furthermore, this contradicts the original design intention of Bitcoin as a value transfer network, and could turn the blockchain into a data storage platform, keeping images, text, and audio away from the blockchain, maintaining the "purity" of Bitcoin for bookkeeping rather than data storage.
In addition, the removal of configuration options by Bitcoin Core (such as -datacarrier and -datacarriersize) is seen as depriving users of their right to choose, enforcing a "paternalistic" policy, while retaining configuration options aligns more with Satoshi Nakamoto's decentralized philosophy of "one CPU one vote."
The intense debate essentially revolves around the ultimate role of Bitcoin in this world. Is it a pure, immutable "digital gold" and a cornerstone of value storage? Or is it a foundational settlement layer that supports limited but useful applications?
OP_RETURN scaling touches on this fundamental philosophical divide. Opponents argue that any attempt at applicability is a blasphemy of "sacredness"; Proponents argue that moderate evolution is the only way to thrive. Times are changing, public chains are constantly rising, and Bitcoin is once again at the crossroads of choice.