Block Stream Mainnet Cutover

Hedera (HBAR) · Releases & Updates · December 9, 2026

Hedera Mainnet switches from Record Streams to Block Streams on December 9, 2026 (testnet Nov 25); mirror node operators must upgrade to v0.164.0+ beforehand.

Hedera, the proof-of-stake public network governed by the Hedera Council (HBAR), plans to cut Mainnet over from the legacy Record Stream format to Block Streams on December 9, 2026 (consensus node v0.80), after a Testnet cutover on November 25, 2026. The date was moved from the earlier October target. Block Streams and Block Nodes change how Hedera publishes transaction and state data: mirror node operators and anyone reading record files directly from the network streams bucket must upgrade before the switch, with hiero-mirror-node v0.164.0 as the minimum version, since older mirror nodes stop ingesting new data at cutover. Apps built on the Hedera SDKs, the Mirror Node REST API and the JSON-RPC Relay need no code changes. Hedera ran a live info session for operators in August on what Block Streams and Block Nodes are and what operators must do to be ready for the Mainnet cutover.

Last verified: · Source: github.com

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