How to unstuck a low-fee transaction with blockchain.info? 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?



This is a complementary question to Why is my transaction not getting confirmed and what can I do about it? which answers the question's broader implications and proposes mitigation mostly focused on Bitcoin Core.
this is a generic answer applying to &quot;light&quot; wallets - I don't know much about the blockchain.info-wallet

There are several approaches that may work.  I'm not sure which methods are most easily available for a user of a blockchain.info-wallet, but probably #0a and #2, followed by #3, #0b and #1b.
0) Wait it out.
0a) Wait for the transaction to go through.  Most likely there will be free capacity in the network after some hours, some days or a week.  In periods with free capacity, even low-fee transactions will pass.  Rarely one has to wait longer than the next Sunday evening.
0b) Wait for the transaction to be forgotten, and then create a new transaction with a higher fee.  In some few exceptional cases (notably around new year 2017/2018 and in 2021) several weeks or even months have passed without any free capacity.  The original transaction may eventually be forgotten by the network.  Some wallets will then offer to create a new transaction, Mycelium will offer to delete the old transaction, and with some luck a &quot;double spend&quot; will be possible - though this is very unreliable as the original transaction may be purposely or accidentally rebroadcast both by the sender, receiver and any third-party.
0c) From some wallets, the most intuitive panic action is to actively rebroadcast the transaction. This probably won't help at all, and it's the exact opposite of 0b, so it's probably not a good idea
1) Double spend with a higher fee (RBF).
1a) Using the &quot;Replace by Fee&quot;-protocol - this probably does not apply to you, but it's arguably the best way to &quot;unstick&quot; transactions.  If the original transaction is marked up with &quot;RBF allowed&quot;, most of the network will accept a replacement transaction with a higher fee.  Not all wallets supports setting this flag, and even fewer has RBF turned on by default - for a good reason, the RBF protocol allows an unconfirmed transaction to be reverted, so using the RBF-flag is a terrible idea if you want someone to trust a zero-conf transaction.  (the RBF-feature has been removed from most Bitcoin Cash software, as they deem it both &quot;harmful&quot; and &quot;not needed&quot;).
1b) Doing RBF/&quot;Double spend&quot; even if the original transaction was not marked as RBF.  Miners (and nodes) are supposed to ignore the double spend transaction - but you may be lucky.  You may need to use specialized software to perform such a double spend.  It may work, either because the original transaction has ended up in a &quot;ghost-like&quot; 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 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 funds they received on a new transaction, with high fee.  This may of course not always be possible, but ...
2b) If not all the money in the wallet was spent, the transaction will typically include two outputs, one &quot;change UTXO&quot; that goes back to the wallet.  If you can spend this one with a higher fee, the transaction may go through faster. Some wallets have a menu option for &quot;accelerating&quot; the transaction through &quot;CPFP&quot;.  In some wallets one can manually decide what UTXOs to include in the transaction. One can also send all the funds in the wallet i.e. back to an address belonging to the same wallet, but the fee for that may become excessive as the wallet may be filled up with &quot;dust&quot; making such a transaction big and costly.  Electrum does support spending some specific UTXO, and Mycelium has the &quot;CPFP&quot; acceleration button.  If you can take out a backup seed phrase from your wallet, it can most likely be used in Electrum or Mycelium.
3) Ask the pools for help.  viabtc has their &quot;transaction accelerator&quot; 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.