First Stratum V2 Block Mined — A Milestone for Bitcoin Decentralization

On June 28, 2026, a Bitcoin miner submitted a block using the Stratum V2 (Braiins BIP-310) protocol — the first such block in the network’s history. This was not a theoretical exercise: it was a fully functional production block, validated by the network, and recorded on-chain. The event marks the end of a years-long development journey that began with the publication of BIP 310 in 2020 and represents one of the most significant protocol-level changes to Bitcoin mining since the original Stratum specification was introduced.

What Is Stratum V2 and Why Did It Take So Long?

Stratum is the TCP-based protocol that miners use to communicate with mining pools. Without Stratum, miners would need to connect directly to the Bitcoin network, which would be computationally inefficient and would result in enormous amounts of orphaned blocks. Since the early days of Bitcoin mining, Stratum (and its predecessor, getblocktemplate-based protocols) has been the dominant way that individual miners connect to pool infrastructure.

The original Stratum protocol (now called Stratum V1) was designed in 2012 and served Bitcoin mining well through multiple generations of hardware. But it has a fundamental architectural flaw: the pool operator has complete control over which transactions are included in the blocks that miners work on. Individual miners contribute hashrate but have zero visibility or influence over transaction selection. This means a pool operator could, theoretically, censor transactions, front-run fee markets, or extract value through transaction ordering in ways that miners cannot detect or prevent.

Stratum V2, developed by Braiins (the team behind Slushpool) and standardized as BIP 310, is designed to fix this. The core innovation is the Encrypted Template Transport (ETT) mechanism, which allows pool operators to send miners an encrypted block template. Miners can then select their own transactions — rather than blindly mining whatever the pool gives them — without ever revealing their selection to the pool operator. This preserves privacy over transaction preferences while still enabling efficient pool communication.

What Changed with the First Stratum V2 Block

The first production Stratum V2 block matters because it demonstrates end-to-end viability of the protocol in a real mining environment. The block was mined by a solo miner using Braiins OS+ firmware on a Bitmain Antminer, connected through a Stratum V2-enabled pool node. The block template was encrypted, the miner made an independent transaction selection decision, and the block propagated and was accepted by the network just like any other block.

In practical terms, this means that — at least in theory — miners no longer need to trust that their pool operator is behaving honestly with respect to transaction selection. The pool can still coordinate hashrate and distribute rewards, but it can no longer secretly manipulate the contents of blocks without the miner’s knowledge. This is a meaningful improvement to the trust model of pooled mining.

Major Pools Are Moving to Stratum V2

Adoption is accelerating. Foundry USA, Antpool, and F2Pool — three of the five largest Bitcoin mining pools by market share — have all announced production-ready Stratum V2 implementations and are actively encouraging miners to upgrade their firmware. According to public statements, these pools collectively represent approximately 45–55% of the network hashrate, making Stratum V2 adoption a network-level phenomenon rather than a niche experiment.

Braiins OS+, the open-source firmware developed by Braiins, has supported Stratum V2 since 2023, and the team reports that tens of thousands of miners have already upgraded. The firmware supports both the original Stratum V1 and V2 protocols, allowing miners to transition without losing connectivity. For Bitmain Antminer S19 and S21 series machines, the upgrade path is relatively straightforward: flash Braiins OS+ and configure the Stratum V2 endpoint in the pool settings.

For WhatsMiner and other MicroBT-based machines, the path is less clear. MicroBT has historically been more closed about firmware development, and Stratum V2 support on WhatsMiner hardware requires either official firmware from MicroBT or third-party alternatives that may not be widely available. This creates an asymmetry where Bitmain machines may adopt Stratum V2 more rapidly than MicroBT machines, which could have interesting implications for market share dynamics among mining pool participants.

Decentralization Implications: Real or Theoretical?

The centralization critique of Bitcoin mining has focused primarily on geographic distribution and pool hashrate concentration. With Stratum V2, a new dimension of decentralization — protocol-level sovereignty — enters the conversation. If miners can independently select transactions, the power asymmetry between pools and miners shifts, and the ability of any single pool to unilaterally censor or manipulate transaction inclusion is reduced.

However, it is important not to overstate the immediate impact. The first production block is a proof of concept at scale, not a transformation. Most mining pools still operate predominantly on Stratum V1, and the fraction of network hashrate running on V2 remains small. The transition will take years, not months. Additionally, the mining pool still controls critical functions: block template construction (even if encrypted), reward distribution, and worker management. Stratum V2 addresses one specific power imbalance — transaction selection — but does not eliminate the fundamental structural relationship between pool and miner.

That said, the long-term trajectory is significant. As more miners migrate to V2, the network becomes more resilient to censorship pressure. If a government or regulatory body were to compel a pool operator to censor certain transactions, a V2-enabled miner could theoretically override that instruction by selecting the censored transactions themselves. This is a meaningful upgrade to Bitcoin’s censorship resistance properties, even if it is not a complete solution.

What Miners Need to Do Right Now

For miners interested in adopting Stratum V2, the immediate action is to check whether their current firmware supports the protocol. Braiins OS+ is the most widely supported option for Bitmain hardware and is available at no cost for personal use, with a paid tier for commercial operations. MarsHub offers Stratum V2 firmware configuration as part of its hosting deployment service — if you are a hosting customer, contact your account manager to discuss upgrading your fleet.

Beyond firmware, miners should also ensure their pool provider supports V2. The three major pools (Foundry, Antpool, F2Pool) all do, and other providers are expected to follow. Connecting to a Stratum V2-enabled pool endpoint requires a specific URL format and may require regenerating worker credentials — consult your pool’s documentation or reach out to their support team.

MarsHub is a leading one-stop miner sales and mining farm hosting platform. We provide Stratum V2 firmware configuration, pool setup, and 24/7 monitoring for all hosted fleets. For hosting inquiries, miner procurement, or protocol upgrade consultations, please reach out to our team directly.

This article is provided for informational purposes only and does not constitute investment advice. Always conduct your own research before making any financial or technical decisions.