TxnHash not found - Unconfirmed transactions

When a transaction request is sent to the blockchain, it stays within the mempool waiting for confirmations.

In most cases, your transactions will confirm. How long this takes depends on the blockchain, how much fee was allocated and the level of congestion in the blockchain.

Get tx by hash responses

• In the Mempool: Get tx by hash returns param blockNumber empty.
• Is Confirmed: Get tx by hash returns param blockNumber with value.
• Dropped: Within ~1h since the broadcast it is removed. Data retrieve attempt return error or nothing.

Dropped example:

//Get dropped ETH tx by hash:
{
    "statusCode": 403,
    "errorCode": "eth.tx.not.found",
    "message": "Transaction 0xc971c441a5b0865688b54918892e844d94c516e51f1b755775d883a170e17ee9 not found. Possible not exists or is still pending."
}
--
//Get dropped BSC tx by hash
{
    "statusCode": 403,
    "errorCode": "bsc.tx.not.found",
    "message": "Transaction 0x2443236fe89da8411d0eaa154726591bf1d204f8acc656e371e6e77d6df92a1f not found. Possible not exists or is still pending."
}
--
//Get dropped NFT tx by hash:
{
    "statusCode": 403,
    "errorCode": "nft.tx.not.found",
    "message": "Transaction 0x2443236fe89da8411d0eaa154726591bf1d204f8acc656e371e6e77d6df92a1f not found. Possible not exists or is still pending."
}

Good to know

When there's a dramatic spike in transaction activity, the mempool can become congested because so many transactions are waiting to be included in the next block. This causes delays of minutes or even hours that will impact the confirmation of your transactions.

In some edge cases, your transactions can be dropped from the mempool, going from status [Pending] to [Rejected] or dropped entirely, so you cannot find it in the blockchain explorer anymore.

This also applies for signed transactions via KMS in daemon mode. Using a custom nonce out of order can also cause getting the tx dropped.