March 20, 2018 at 4:00 pm #1210
I’ve sent a transaction from blockchain.info, but accidentally included too little fee. What can I do to cancel the transaction or speed up the transaction’s confirmation?March 20, 2018 at 4:01 pm #1212
There are several approaches, none of them are bullet-proof. I’m not sure which methods are most easily available from the blockchain.info wallet, but probably #0 and #2, followed by #3 and #1b.
0) Wait it out. Even in late 2017, every now and then there is still almost free capacity from time to time where even low-fee transactions will pass; typically Sunday evenings. After ~2 weeks the transaction will eventually be dropped by the network – though it’s possible to rebroadcast it, both by the sender, receiver or any third-party.
0b) Rebroadcast: it probably won’t help, but while you’re anyway waiting you may try to actively rebroadcast the transaction (not sure if the blockchain.info-wallet supports it – it may be done through external software though).
1a) Replace by Fee (RBF): By 2017 many miners will accept a double spend if and only if it’s done through the RBF protocol. To use RBF, the original transaction should have been sent as a “replaceable” transaction – only a few wallets supports this, probably blockchain.info does not support this, so this probably doesn’t apply to you. I’ll still leave it here as it arguably is the best way to “unstick” transactions. RBF can also (theoretically – not supported by many wallets) be used to retract an existing zero-conf transaction. It may be a bad idea to set all outgoing transactions to be replaceable by default, if you buy coffee with an RBF-transaction you may end up not getting the coffee until it’s cold.
1b) Double-spend with a higher fee; this normally shouldn’t even be possible unless the original transaction is marked with RBF, but it may be worth trying out anyway, perhaps you’ll be lucky. You may need to use some other wallet or even specialized software to do a double spend. It may work, either because the original transaction has ended up in a “ghost-like” state where it’s known by some nodes but not others – maybe some miners are unaware that you’re doing a double-spend – or it may work because some miners deliberately accepts double-spent transactions as long as they can earn more fees on it.
2) Child Pays for Parent (CPFP): if a new transaction is made with a high fee, building on top of the old transaction, most of the miners will include the whole chain of transaction in the block they’re mining at.
2a) Get the receiver of the funds to spend the amounts they received on a new transaction, with high fee. This may of course not always be possible, but …
2b) If the transaction didn’t empty the wallet completely, there should be a “change-UTXO” in your wallet, if you can manage to spend this one with a high fee the transaction will probably go through faster. Some wallets will give you the option to do a CPFP-transaction, if it’s not explicitly supported you can always try to make a new transaction spending all of your wallet funds (you may send it back to the same wallet eventually). Beware, if you’ve been using your wallet for a while and never emptied it completely, this will most likely hurt – fees may grow out of hand as the wallet is filled up with dust. The transaction may be tweaked to include only the change UTXO. I don’t know blockchain.info much, in worst case you may move the private key or the wallet seed to some other wallet. Electrum does support spending some specific UTXO eventually.
3) Ask the pools for help. viabtc has their “transaction accelerator” at https://pool.viabtc.com/tools/txaccelerator/, antpool.com also has some similar service, there even exists services where one can pay by credit card to get the transaction prioritized.
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