- Bitcoin Core 30 will raise OP_RETURN data limits from 80 bytes to nearly 4MB by default.
- Reformist developers say the change boosts innovation, while critics warn of blockchain bloat.
- Node operators can revert to smaller limits, but most nodes follow the default configuration.
Bitcoin Core developers have locked in a major change for October. The next version, Core 30, will raise Bitcoin’s OP_RETURN data limit. This decision brings an end to months of heated debate within the developer community.
The change will expand the default data carrier limit from 80 bytes to nearly 4MB. This would enable significantly more non-financial data to be stored on the Bitcoin blockchain. Antoine Poinsot and Peter Todd led the push for the increase. They believe this change will help grow Bitcoin’s functionality.
On the other side, developers like Luke Dashjr opposed the shift. He argued the blockchain should only store data for BTC transfers. He called large data transactions irresponsible and a risk to Bitcoin’s design. Opponents also warned about potential corporate misuse and storage overload.
Despite these warnings, reformist developers continued to move forward. Gloria Zhao announced that Core 30 will launch in October. With it, the new 4MB OP_RETURN limit becomes the default setting. This move is seen as a major win for the reformist group. However, developers added one compromise. Node operators can still manually adjust their settings, allowing them to revert the limit back to the smaller size. But most Bitcoin nodes use the default settings. Therefore, the majority of the network is likely to adopt the 4MB threshold.
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The OP_RETURN field allows users to embed arbitrary data in transactions. Since 2014, Bitcoin Core has limited this to 80 bytes. This had helped keep Bitcoin’s chain lean and focused on transactions. Raising the cap to 4MB marks the first major expansion of the limit. The feature will not affect how Bitcoin validates transfers. But it could influence how people use Bitcoin for data storage. Reformists say it opens the door for innovation. Critics say it distracts from Bitcoin’s true mission.
The change comes after long-standing tension between the two camps. The reformists want Bitcoin to evolve. The conservatives aim to preserve its original purpose. The decision to allow configurable settings was a last-minute concession. Earlier versions of the proposal didn’t allow any manual override. Still, the shift in the default behavior is what truly matters; it means most Bitcoin nodes will automatically adopt the new setting once Core 30 launches.
