How do I cancel my blockchain transaction (still unconfirmed)?

  • I am using blockchain.info.

    I have made a bitcoin transaction of 22.00883562 BTC to the address 1A9eUAc78tGx65X3CuC9WfSKXXgxjU8ccC.

    You can see the transaction at https://blockchain.info/tx/97c1af82111cdcf17f878eb6df20c17c59c1b1fc04e8cdce36b8ac6c6d1c969a

    I have paid a 0.001 fee but it has been almost 30 hours and it still shows "Unconfirmed".

    What could be the error? Also, more importantly, how do I cancel the unconfirmed transaction and get back my coins?

    It seems like your transaction has been confirmed now.

    @GregHewgill, that's irrelevant. The question was how does one cancel an unconfirmed blockchain transaction.

    Well, that answers the "What could be the error?" question - there was no error.

    @GregHewgill, considering that he paid 0.001 (10x more the norm) fee, staying "Unconfirmed" for 30 hours is extremely weird and I would say there's a high chance that there's an error with blockchain.info.

    22 BTC man... you're rich!

  • Cancelling unconfirmed transactions is easy. Just submit a higher fee double-spend transaction. For example: if you send a 0-fee transaction it could take a day before 1 block mines it. Then you send another transaction with the same inputs that just sends the money back to yourself. On this transaction you put a higher fee. This becomes more likely to be mined and will get included in the blockchain - invalidating the slower-to-confirm original.

    How do you double spend if you are sending from a wallet and now no longer have that same amount? IE I've sent from an XRP wallet to Changelly to convert it to BTC over at Coinbase. Now I don't have enough XRP to send.

    This. In theory looks nice, in practice but really

    @LeonGaban: I believe that in that case, you're screwed. Anybody knows a workaround?

  • You cannot cancel an unconfirmed transaction. When a transaction has been transmitted to the chain, it's unstoppable. Luckily everything went well for you I see, and it was probably an error on blockchain.info, as pointed out in the comments.

    You can cancel an unconfirmed transaction - by double spend this input, therefore original tx will be canceled. Moreover, even if transaction is included in block, it can be canceled - all you need to do is to mine two consecutive blocks without this tx. Therefore, the first block will be orphaned, and all the transaction it has will be unvalidated. This is the very reason we should wait for 6 confirmations.

    Ahh, I didnt know that. But isnt it quite easy to cancel your BTC transaction in the supermarket (when its implemented), a few seconds after your transaction? That would be a huge disadvantage

    I didn't say it is easy, only that it is possible. I think we can pull this on our own. All we need to do is to buy cheap VPS across the globe (digital ocean?), and using ssh - double spend our coins to our address as soon as we initialize transacion in the supermarket. This is double spending. Note that the bigest BTC processor, Bitpay, does accept 0/unconfirmed txs, because they understand the risk and pay for double spends from their own pocket.

    Cancelling unconfirmed transactions is easy. Just submit a higher fee double-spend transaction.

    @Maciej Mączko : I like "mine two consecutive blocks". So easy! Would you please lend me your (super)computer for a day, so that I mine a few blocks, just for sport? :)

    @PPC Thanks for your comment. As I said _three years ago_, it isn't easy, it is (was) possible. Back then, strong ASIC would give you two consecutive blocks once in a month.

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Content dated before 6/26/2020 9:53 AM