258: txn-mempool-conflict

[JuliusPrime]

When trying to send a doublespend transaction, it does not accept with error 258: txn-mempool-conflict
How many old transaction can hang in before removal?

[Pmalek]

You need to wait a few days before it expires from the mempool or try from a different blockchain service provider as suggested in this source > https://www.reddit.com/r/Bitcoin/comments/4xcf19/258_txnmempoolconflict/

[JuliusPrime]

But what are you trying to achieve with double-spend attempt? If your goal to make a transaction confirmed, you can use increase your transaction fees with RBF option.

Sorry, sent without RBF