I get this when trying to send the raw transaction (push it) to my node:
bitcoin-cli sendrawtransaction 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
error code: -26
error message:
258: txn-mempool-conflict
I've seen this code: 258: txn-mempool-conflict before... IIRC, the last time, it was because one of the inputs of the transaction was already used for a different transaction that was already sitting in my mempool (aka, double spend)
So what can i do now
It doesn't seem like blockchain.info has a double spent transaction in it's mempool, however
https://live.blockcypher.com/btc/tx/42617b56cba1ec75f80e62e0af4f7e30cdb61fbf3a3a1a9ac0a640c37c6dd2f0/ says that there are only a limited number of nodes that have this transaction in their mempool.
What *could* have happened is that one of the inputs for this transaction was already used in a different transaction a couple days ago... This previous transaction remained unconfirmed, dropped from the mempool of most nodes (like blockchain.info) but not from others.
If this is the case, the first transaction *should* be dropped by most nodes in a couple of days, and you *should* be able to re-broadcast this one.
Once again: this is only a theory!