Sia v2: Hard fork on June 6, 2025.
The Sia network is at a critical juncture. On June 6, 2025, the long-awaited v2 hard fork will activate, marking one of the most transformative updates in the network's ten-year history. This is not a minor fix or a deployment of an additional feature. It is a fundamental redesign of Sia's consensus code, transaction formats, and renter-host architecture, paving the way for a faster, more flexible, and promising decentralized cloud.
But to participate in what comes next, you need to upgrade.
Whether you are a renter, host, or Siacoin holder, continuing to use the network requires transitioning to new software compatible with v2: renterd, hostd, and walletd. Without an upgrade, your node will stop synchronizing, your wallet will be frozen, and your contracts will become obsolete.
The Sia v2 hard fork is more than just a version change — it is a revival. A cleaner, faster, more capable protocol designed to meet the needs of a decentralized future. But to be part of it, you need to upgrade.
Why v2? Modernization for the future
The v2 hard fork is more than just a technical upgrade — it is a complete overhaul of the Sia network architecture that improves performance, scalability, and usability across the board. By transitioning to a more modular, efficient foundation, v2 opens up possibilities that were previously impossible or impractical.
This update brings radical changes to consensus verification, file transfer protocols, and application design. Each part is designed to optimize user experience and simplify maintenance and network expansion. Together, they lay the foundation for the next generation of decentralized storage.
Utreexo: Compact and fast blockchain state
The main innovation in v2 is Utreexo, a cryptographic state accumulator that replaces the traditional UTXO database. Instead of storing every unspent output in a huge local database, Utreexo compresses this state into a small proof, allowing new nodes to synchronize in minutes rather than days.
Benefits include:
Fast synchronization: nodes validate blocks without complete history.
Light clients: full node security on mobile devices and browsers.
Parallel synchronization: provides initial loading based on checkpoints.
Modular verification: simplifies the extraction and verification of consensus logic.
Utreexo enables faster adaptation, lowers the barrier to running nodes, and improves decentralization by allowing lighter clients to fully participate in the network.
RHP4: More advanced and intelligent file transfer
The new Renter-Host Protocol 4 (RHP4) is designed for speed, usability, and flexibility:
Simultaneous uploads/downloads
Access via browser through QUIC
Prepaid bills and delineated contract management
This paves the way for new tools, such as indexd, where contract management can be outsourced while maintaining decentralized and private uploads. RHP4 also enables:
Early contract termination
Power reservation
Transferring funds between renewals
New modular application stack
Sia v2 is a modular trio of applications, each designed for a specific role:
renterd - For uploading files. Scalability and ease of deployment, browser support, and SQL-based metadata.
hostd - For providing storage. Enables faster uploads, better monitoring, and easier setup.
walletd - For managing Siacoin. Uses a new 12-word seed format, supports hardware wallets, and offline signing.
Each application is independent and optimized for its task. No more monolithic siads. Users install only what they need, and developers get better APIs, cleaner codebases, and room for innovation.
A new foundation for what comes next
The v2 hard fork is not the end of Sia's evolution; it is the beginning of a new phase designed for scalability, accessibility, and long-term growth. With foundational technologies like Utreexo and RHP4, the ecosystem can now support light clients, instant synchronization, browser-based uploads, and third-party services that simplify the user experience.
This progress means that users will soon be able to interact with Sia just like traditional cloud storage — only with greater privacy, more reliable security, and full ownership of their data.
The future of Sia is lighter, faster, and more open than ever, but it starts with modernization.
Don't wait for the last block. Upgrade
