isBlockhashValid

isBlockhashValid tells you whether a given Solana blockhash is still recent enough to anchor a transaction. You pass a base-58 blockhash and the node replies with a boolean wrapped in an RpcResponse: true if a transaction built on it would still be accepted, false once it has aged out (after roughly 150 blocks at ~400ms slots). It is a cheap pre-flight check that saves you from spending a SOL fee broadcasting a transaction the cluster would reject. Call it on TheRPC at https://solana.therpc.io/YOUR_API_KEY.

Use cases

• Before a resend, check the existing blockhash and re-sign with a fresh one from getLatestBlockhash only when this returns false, avoiding a wasted broadcast.
• Validate a cached blockhash inside a long-running send loop so the loop knows when its transactions have become unsendable.
• Replace the removed getFeeCalculatorForBlockhash validity check, which used to double as a way to test whether a blockhash was still alive.

Parameters

Response

Example request

1curl https://solana.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5  "jsonrpc": "2.0",
6  "id": 1,
7  "method": "isBlockhashValid",
8  "params": [
9    "AdQJjJ2zT...",
10    {}
11  ]
12}'

Errors & troubleshooting

Common pitfalls

• A false result means the blockhash has expired. Fetch a new one with getLatestBlockhash, rebuild and re-sign the transaction, then resend.
• The boolean is wrapped in an RpcResponse under result.value. Read that nested field, not a bare top-level boolean.

Supported networks

• Mainnet
• Devnet

See also

• getLatestBlockhash
• getFeeForMessage