Hedera Block Nodes in Private Preview

By Nana Essilfie-Conduah

Private Preview Deployment and Timeline

Block Nodes — launching in 2026 — will become the decentralized, cost-efficient data lake of the Hedera network. They will replace today’s large cloud bucket storage and enable faster, cheaper, and more flexible access to network data. Mirror nodes will be able to stream the unified HIP-1056 Block Streams format (which will fully replace the legacy record file format) directly from block nodes to obtain network data.

Mirror Node operators are directly affected.

Mirror Node operators must prepare now for the transition from record files ➜ block streams. The minimum required block stream compatible Mirror Node version will be v0.148.0 (available February 2026).

To avoid data ingestion interruptions during this transition, Mirror Nodes must upgrade to a version that supports the new Block Streams format.

Migration Requirements and Deadlines

Key deadlines:

• Operators will have three months from February 2026 to May 2026 to prepare and validate a block stream compatible version
• Operators must deploy a block stream compatible mirror node version before the consensus node upgrades to v0.74.0, planned for June 2026

Failing to validate and upgrade before this window will result in:

• Loss of network data ingestion
• Inability to support future state queries and services
• Operational outages for any systems reliant on Mirror Node APIs

To validate this migration, a Block-Stream-compatible Hedera Mirror Node will be deployed in February 2026 and will run in parallel with the current record-file-parsing mirror node to demonstrate full operational equivalence.

Block Node Deployment Status Update

In November 2025, the Engineering team deployed a private preview of council-operated Block Nodes across previewnet, testnet, and mainnet. This major milestone begins network validation of HIP-1056 Block Streams and HIP-1081 Block Nodes.

Today, these preview block nodes run in parallel with existing operations, which continue to rely on record files and full-history cloud buckets. As expected in an early preview some capabilities remain incomplete e.g. blocks are not yet signed with HIP-1200 hinTS threshold signature verification.

Over the coming months, engineering teams will refine software, hardware recommendations, and deployment patterns. Access will be opened to community builders in Q1 2026, allowing Mirror Node operators to start testing integrations early in the previewnet and testnet environments.

Once enabled block nodes will provide:

• Immediate streaming access to exported consensus network data
• On demand retrieval for both recent and historical block data
• Future support for filtered queries, allowing operators and builders to request and store only the portions of block data they care about
• State services such as State Proofs and state snapshots queries

Architectural Changes for Mirror Nodes

Under the future Block Node model:

1. Cloud buckets → Direct Block Node subscription

Mirror Nodes will stop downloading record files and instead:

• Subscribe directly to a Block Node for live block items
• Receive block data as it is produced, significantly reducing latency
• Retrieve historical data from any Block Node without having to rely on centralized storage

2. Limited-history cloud buckets → Block Streams ingestion

Mirror Nodes with limited to no access to block nodes will be able to ingest recent blocks from limited-history cloud buckets using the Block Streams format. This serves as a backup alternative during the transitional phase whiles the number of block nodes are increased over time.

Why operators should care

This architecture:

• Eliminates the cost and maintenance burden of large cloud bucket downloads
• Ensures operators keep receiving the full network history
• Future-proofs Mirror Node operations for new services such as State Proofs, filtered block queries, and consensus-equivalent state lookup

If Mirror Node operators do not upgrade, data ingestion will fail once block streams become the canonical network data format.

Key Takeaways

• Block Nodes are now in private preview across previewnet, testnet, and mainnet, validating HIP-1056 and HIP-1081.
• Community access begins Q1 2026, enabling early testing and integration.
• A block-stream-capable Mirror Node will be released in February 2026.
• Mirror Node operators must upgrade to v0.148.0 before May 2026, ahead of consensus node release v0.74.0 in June.
• Staying current with mirror node versions ensures continued data compatibility and unlocks the benefits of the new block streaming architecture.
• Mirror node operators are strongly encouraged to review HIP-1056 Block Streams and HIP-1081 Block Nodes in preparation for the migration.

Reference Links

• HIP 1056: Block Streams
• HIP 1081: Block Node
• HIP 1200: The hinTS threshold signature scheme
• Block Streams & Block Nodes: Advanced Insights & Implementations | HederaCon 2025 | Technical Stage
• Hiero Block Node Github Repository
• Introducing Block Streams: A Unified Data Stream Capturing the Comprehensive History of the Hedera Network
• 5–22–25 Technical Community Call
• 9–25–25 Technical Community Call: Blockstreams, Blocknodes & TSS, AI on Hedera, and Hackathons Update
• 10–30–25 Technical Community Call

Hedera Block Nodes in Private Preview was originally published in Hedera Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.