bitcoin core v30 coming in october - here's what's changing and what people are saying

Bitcoin core is releasing version 30 in october with some notable changes. The biggest one is removing the 80-byte cap on OP_RETURN, which is the part of transactions that allows embedding arbitrary data.

currently there's an 80-byte limit on how much data you can attach to a transaction. v30 would lift that restriction entirely.

what core developers are saying:

Gloria zhao, a bitcoin core maintainer, says this change aligns the software with what miners already accept anyway. She argues that OP_RETURN data is "prunable and less harmful" than other methods people use to store data on-chain.

The core team is framing this as network neutrality - letting the fee market decide what gets included rather than imposing artificial restrictions.

what critics are saying:

Bitcoin knots developer luke dashjr and others argue this opens the door to more data spam on the blockchain. They're concerned about non-financial transactions crowding out actual payments and increasing the burden on nodes.

Some critics also worry about the potential for illicit content being permanently recorded on bitcoin if the size limits are removed.

Jimmy song responded that embedded data isn't "readily accessible" and running bitcoin software doesn't make you responsible for whatever data might be included.

the numbers:

bitcoin knots nodes have grown significantly this year - from about 400 at the start of 2025 to over 4,700 now. That's still small compared to the 22,496 total public nodes, but it shows growing interest in stricter policies.

The debate basically comes down to whether bitcoin should optimize for payments only or allow broader use cases. Different implementations are taking different approaches to this question.

October will show how many node operators actually upgrade to v30 versus sticking with older versions or switching to alternatives like knots...