A Child Pays For Parent (CPFP) transaction is one where you pay a high fee to incentivize miners to also confirm the unconfirmed transaction from which you are drawing the inputs i.e. the parent transaction. Usually you can do a CPFP quite easily from within the Electrum interface (see bump the fee). However, in some cases that is not possible so you can try doing a manual CPFP transaction.
- First ascertain that CPFP is possible for your transaction. Right click on the unconfirmed transaction on history tab and choose to view details. In the details window see if any of the outputs have addresses highlighted in yellow or green. Note down those addresses. Also note down the size in bytes of this transaction and the fee you paid.
- Go to tools menu > preferences > transaction tab > uncheck spend only confirmed coins.
- Go to receive tab and grab a receive address. You will use this in the next steps to send yourself money.
- Go to view menu > show coins, switch to coins tab and select coins associated with at least one of those output addresses from step 1 and coins sent to any other address in your wallet. You can hold down ctrl and left click to select multiple entries on that tab. Once you have made your selection right click and choose spend.
- It’ll take you to the send tab where you enter the receiving address from step 3 above. Move the fee slider all the way to the right and send these coins to yourself.
- Optionally: You can also set a fee manually if you are up for it. Click on preview to find out the size of the child transaction in bytes. Then, keeping in mind the fee you paid for the parent transaction (step 1), calculate a suitable fee based on market conditions that will be enough to pay for both transactions. Then go to tools > preferences > fees tab and check edit fees manually and manually enter the fee on the send tab.
Note: If there are no yellow or green addresses in the transaction outputs (step 1) then you can’t do a manual CPFP either and you’re only options are 2 and 3 here.