Replace-by-fee via RPC #11973

Is it possible to replace-by-fee existing transaction in mempool purely using RPC commands? If yes, then how?

You can use bumpfee if you purely care about increasing the fee of a transaction (although I would never rely on the ability to do this, as the command is very unreliable).

The more general approach would be to use createrawtransaction

Also this question would be best put on stackoverflow, not as a bug report

Replace-by-fee (bumpfee or via createrawtransaction) is only possible for a transaction where you have previously "enabled" RBF (means the transaction does signal BIP125 RBF via inputs nSequence).

If you haven't had -walletrbf enabled or did check the checkbox in Qt (or used the right RPC arguments), you can't use RBF reliable.

Another way how to unstuck transactions is by CPFP (child pays for parent) via Qt/CoinControl (I have done that serval times and assisted some users with that). You basically choose the stuck transactions change output as a new input for a self-to-self transaction and pay twice the required fee.