Last Valid Block Height
Pronunciation: LAST VA-luhd BLOCK HYTE
Definition
Last valid block height is the final chain height through which a transaction's referenced validity context remains acceptable for processing. The value is a block height, not a wall-clock timestamp and not necessarily a slot number. Network progress determines the available submission window. A transaction may still fail earlier for fees, account state, signatures, or program errors.
Overview
Meaning and scope
Last valid block height is the final chain height through which a transaction’s referenced validity context remains acceptable for processing. The value is a block height, not a wall-clock timestamp and not necessarily a slot number. Network progress determines the available submission window. A transaction may still fail earlier for fees, account state, signatures, or program errors.
Mechanism and operation
Last valid block height commonly appears in Solana transaction workflows. Clients should retain the blockhash and its matching last valid block height together, poll signature status, and compare current block height before retrying. After expiry, they must obtain a fresh blockhash and re-sign because the signed message changes. Unknown, pending, included, failed, replaced, and finalized conditions need separate handling, together with a recovery procedure for transactions whose observed state conflicts across providers. User-facing status should describe what is known without overstating settlement. Last Valid Block Height should be represented as a sequence of observable states rather than one success flag.
Practical payment example
A Solana transaction expires because the cluster passes its last valid block height. The merchant creates a fresh signed attempt only after confirming the previous signature cannot later settle the same order.
Operational checks
Submission, peer acceptance, block inclusion, execution, confirmation, and finality provide different evidence, and a transaction can advance, stall, be replaced, or disappear from the canonical chain between those stages. Repeated callbacks, node disagreements, reorganization, and delayed receipts must not create duplicate credits or irreversible state transitions before the required network evidence is available.
Distinctions and limits
When an application fetches a recent blockhash, the response includes a height after which transactions using that blockhash are considered expired and should not be accepted.
Related reading
Related definitions: block height, block.
Example
A Solana transaction expires because the cluster passes its last valid block height. The merchant creates a fresh signed attempt only after confirming the previous signature cannot later settle the same order.
Comparison
When an application fetches a recent blockhash, the response includes a height after which transactions using that blockhash are considered expired and should not be accepted. The value is a block height, not a wall-clock timestamp and not necessarily a slot number.
Key Takeaway
Last valid block height bounds a transaction's usable blockhash window, requiring fresh construction and signatures after expiration.
Sources
- Ethereum Documentation: Transactions — Ethereum Foundation (2026-07-30)
- Bitcoin Developer Guide: Transactions — Bitcoin.org (2026-07-30)