Bitcoin Forum

It has been said sometimes that a Bitcoin transaction can be cancelled or reversed using for example double-spend.
Is it still possible? If Yes, how? If No, Why?
Especially when you sell services and goods and accept Bitcoin payment, you are worried about this.
So it should be a good idea to discuss this topic.

You can't cancel or revert a transaction.

However, there are a couple "tricks" you can pull while a transaction is UNCONFIRMED.

For example, you can create a (very) low-fee transaction, and broadcast it to as little nodes as humanly possible. Then, create a new transaction, using the same unspent outputs as input but funding a completely different address as the first transaction. You can create this secondary transaction with a much higher fee and broadcast it to as many nodes as possible.
If you do this, there is a decent chance a miner will put the second transaction into the block he's currently working on instead of the first one. And once one of those transactions ends up in a valid, broadcasted block that's been added to the blockchain, the other transaction is automatically "voided". It's using unspent outputs that are no longer in the UTXO set, so the unconfirmed tx becomes invalid.

If you're setting up a service, it's always a good idear to wait for at least 1 confirmation before sending goods or services. For expensive products, you might even chose to wait 3+ confirmations ( 6+ for the really paranoid shop owners). Once a transaction has a couple of confirmations, there is no way of cancelling or reversing it.

An already confirmed transaction that has been included in a block can't be cancelled.


It is a better idea to search before starting a new thread:
https://bitcointalk.org/index.php?topic=1922415.0
https://bitcointalk.org/index.php?topic=1901899.0
https://bitcointalk.org/index.php?topic=1238034.0
https://bitcointalk.org/index.php?topic=151430.0
https://bitcointalk.org/index.php?topic=1742325.0
https://bitcointalk.org/index.php?topic=1177722.0
https://bitcointalk.org/index.php?topic=1516140.0
https://bitcointalk.org/index.php?topic=1012583.0

Of course, a search is always helpful. I agree with you!
However, these threads are outdated, and in some of them, it has not been clearly answered.
The technology is moving forward and we need to know what is the actual stand.
I've read about double spending and found this for example


But is there someone who has been able (recently) to cancel a broadcasted transaction?

or is it definetely that there is NO WAY to cancel a transaction?

Thus it makes sense to discuss it again.

I have a habit of cheaping out on fees when i move funds between my own wallets. Nowadays, i always opt-in RBF, which makes it very easy to create a double spending transaction with a higher fee and broadcast it, but about a year ago, i did have to create new transactions doublespending the unspent outputs used and input of my own transactions several times. It was during the spam attack and the astronomical fees, and before opt-in RBF was adopted in my wallet, so many of my low-fee between-my-own-wallet transactions got "stuck". doublespending was the fasted way of fixing these problems.

It can be done, but like i said: if you wait for 1+ confirmations, the transaction can no longer be "cancelled" this way.

           I actually like your idea about double spending, now back to the topic, i guess there is no way it is reversable, that is why you need to check it multiple times before making a transaction. There are also notifications that tells each user that it cannot be reversed, so you have to be aware, once it is confirmed, there is no turning back, and no regrets when it is done.

If the transaction is confirmed already then you cannot undone it. But otherwise I read some tricks that will make some adjustments while the transaction isn't confirmed yet. I found it in the first page of this this thread but I didn't verify since you need to do it accordingly.

You don't need to worry about double spending. If you make a transaction using bitcoin there isn't anyway to cancel the request. Once it is made it is made. The only way to stop a transaction by double spending is if the transaction isn't confirmed. In the real world people wait until transactions are confirmed in order for it to mean anything.

bitcoin transaction that we have done will not be canceled, this is the system that I think is very good from bitcoin after we do bitcoin transaction then we just wait for the results of the transaction

After one block confirmation it becomes impossible to reverse, that is why before to carry out a transaction it's best you be 100% sure of the address and other necessities, many have unknowingly sent bitcoins to the wrong address or to a scammer, manual checking is also necessary sometimes

I visited this site and quickly scanned the explanation they gave on how they cancel transactions, and all i can say is: that's not how this works... As soon as a transaction is confirmed, it's allmost impossible to cancel the transaction unless you own enough asic's to do a 51% attack... Any site claiming otherwise are a potential scam

It is trivial to do before the first confirmation. You'll require hundreds of millions in mining equipment after the first one. This is not how bitcoin used to work a few years ago so a lot of merchants get scammed.

the transaction has taken place then it cannot be canceled. like we pulled the trigger once pulled then it can't be canceled. be careful before making a transaction and don't rush into doing a transaction before we are sure of everything we do.

You cant reverse or cancel a bitcoin transacton as far as i know,but there are tricks to not totally cancel bitcoin transaction but to remain unconfirmed and later on get back on the senders wallet i dont know how they do that but thats what i only know.

just as you will transfer money from bank A to bank B where after the confirmation notification appears and you confirm that your transaction is correct then you cannot cancel the transaction because your transaction is being processed and cannot be canceled by the system

This one is not a potential scam, it's a 100% genuine scam

https://i.imgur.com/s02Bgz5.png

Not only is their claim hilarious, but their script is also bugged, that address I posted and the tx are not 521 days old, they are 9 years old. Furthermore, they ask you for "Private key or your seed pharse" , yeah, pharse :D.

Fortunately, it seems that the payment address is always the same, no matter what you try and till now it has 0 transactions.

Personally, I do not believe that bitcoin transaction can be cancelled after it's sent.
My assumption is that ...miners start the mining of bitcoin immediately it's the sent button is clicked.
There's no way of knowing which miner so as to signify to the person to cancel the transaction or reverse it.
It's just too complicated.

Bitcoin transactions cannot be cancelled. The process is irreversible and this is how the network has been built.

Personally,  I find that as a good thing, as I wouldn't want to see that a transaction I had in my wallet during the night has been cancelled in the morning.

The transaction through bitcoin is a single way system. Once transferred will not get back an access to the funds anymore until the receiver manages to send back to the sender. With this before making a bitcoin transaction it is a must to be much careful. There is a possibility to cancel a transaction if it hasn't got connected to the block.

I was thinking of what is the one drawback which bitcoin has ?  The only drawback is that if you sent the amount to wrong address or wrong amount to the right address even, the process cannot be reversed and therefore one should be extra careful when sending bitcoins to any address.

This is why unfortunately some binary options moved to cryptocurrencies, damaging the reputation of the whole crypto community.

as long as I use Bitcoin I have never found a way to cancel a transaction, and I don't think we can do it, what I know is that there will never be a double transaction in Bitcoin.

Very clear analysis I know this will work effectively, and my question is what if you have balance on your account after the second transactions have been achieved that can found the amount that the first transaction demands what will happen in this situation?

That is not a cancel, and is not a reverse, that is just what you yourself said: A double spend. Only one may enter the blockchain, and that obviously is the one paying the higher fee, even when broadcasted later. Your window of opportunity could be a a small as the time remaining to find the next block, so its not even guaranteed you would succeed.

Unfortunately the likely people making the mistake probably didn't even bother lowering the tx fee shrinking their chance.

Moral of the story: triple check where you send your coins to.

You CANNOT reverse or cancel a tx.

So, is it your scamsite, or are you just a payed shill? What this site portaits is theoretical impossible, so if you keep insisting something theorethical imposible has happened, the only logical conclusion is that you're trying to scam the users of this forum...

i wish it could have been possible to do. but any spent bitcoin cannot be cancelled. thats why it is always advisable to check well and be sure of where you are sending bitcoins to before clicking send button. in case of making payment in a store for good purchased, this would have been stated clearly to be mindful of sending bitcoins to wrong address or QR code scanning can be used this will avoid any issues of sending to wrong address.

Merit you for a great explanation, I have not encountered a transaction where I could wish or plan to reverse, but this one is going to be a big help if ever I have I encounter something like this, this is a big help for those selling goods and offering services.

Bitcoin transactions cannot be reverse or cancel. This is online transaction and when you pay bitcoin using online it is straight to the sellers system especially when you transact at the big business stablishment or company that already upgrade their system  but when you are have a bitcoin transactions to a person to person buy and selling  I think there is possibility that you may reverse your money by sending back your bitcoin.

Double spending and reversing a transaction is actually two separate things. In a double spend you can spend the same bitcoin more than once. <This can happen if you manage to gain more than 51% of the total hashing power of all the mining that are done>  https://www.blockchain.com/en/charts/hash-rate  <Pretty expensive way to perform a double spend  ::) >

Reversing a transaction is similar to a chargeback with a credit card and this is not possible with Bitcoin under normal circumstances, when say 1 or more confirmations has been received. <Something that most merchants love about Bitcoin>  ;)

we already know that all the bitcoin transactions that have been running, it is impossible to cancel because at that time the data block has begun to be resolved and this is not a transaction like what happens to cash that we can withdraw, so be careful in making wise transactions every time we place an order for bitcoin transactions, we know the risk

There is no way to do that, that is why you need to transact to people you trust or company that has a good buyer good rating, this is an advantages and disadvantages of blockchain and Bitcoin it's decentralized like PayPal or other online company where they can reverse the transaction for you if there is error in sending it.

I agree with you, that it is impossible to cancel or reverse every bitcoin transaction that's why it is very important for us to study it first before doing any transactions so that we would not regret for what we have been done but we will receive a benefits from it because in that way we can use and transact any amount of money wherever we are.

If that was possible i don't think bitcoin will have the popularity right now. It is what it should be also. I mean if you do a money transfer can you reverse that?

This is one of Bitcoin's strongest and most liked feature, without this feature and decentralization, Bitcoin will not be this popular, so be sure that before you send that coins, you are 100% sure that you want to do that unless you are sending it to a company which offers reversal.

I think once it is already sent or the transaction is already out,
There is nothing that we couldn't do with it but to wait till it is confirmed.
We couldn't reverse or cancel a Bitcoin transaction once it is made.

Not possible as far as I can tell . Though I have read couple of suggestions about making this possible only on side chain or with other applications while leaving the main chain irreversible. If you understand the idea behind irreversible transactions, you wouldn't worry too much about it.
Only unconfirmed transactions can be reversed I think.

bitcoin transaction and blockchain technology in general is known for its irreversible and un-cancellable  transaction feature so when a transaction is initiated in the blockchain space, it does not get cancelled or reversed as the technology was not designed in that light

Once you click on the send button, your transaction can't not be reversed or cancelled. I wish this aspect of Bitcoin could be upgrade to help people cancel their transaction request if the transactions has not yet been confirmed by the blockchain network. Such upgrade is going to transform the whole nature of the bitcoin ecosystem.

Think before you click as everyone says.
Always to just not triple check the transaction before sending it as it is permanent and cannot be undone.
Blockchain technology is great, once done it will be history!

Verified of confirmed transaction cannot be reversed because it is already mined and added to the Block. This is why several attempts has been made on the forum to create awareness on the necessity to double-check and if possible check as many times as possible the amount to be sent and the receiving address before sending.

Well probably for those transactions that are still in queue yes, but for already completed transactions, i highly doubt that it'll change. Users should be cautious in pressing that send button for now to avoid losing coins since there's no way it can be revoked once completed.

can't, and so far I've never seen anyone who can do it.
Therefore, it is expected to be careful when dealing with bitcoin transactions, make sure everything is correct and in consciousness
If there is a mistake then it will be complicated and make you regret

Sorry mate but as far as I know there are no ways to reverse a transaction once it has been procesed into blockchain...I did a mistake like this once and since then when I make crypto payments I make sure that every input is corect before sending it...

There are some rigid and non-modifiable certainties for bitcoins: one of these is the immutability of a transaction. Once done, you can't go back. Luckily.
This is precisely one of the greatest values attributed to bitcoin.

No, bitcoin cannot be reversed or canceled. However, there will probably be services to reverse or cancel bitcoin transactions in the future as a layer 2 solution. Bitcoin's irreversibility is what makes it both valuable and frightening to the average person.

In hitbtc, you can. Once you ordered to send the money and confirmed it you can always cancel it but the fee will be reduced. So if your money is. 05 btc and the fee is .0015 btc then when you cancel it, the funds you can get is only. 0485 btc.

It can be done by the exchanges only as they will do by their own pocket but in blockchain bitcoin transaction cannot be cancelled once it is confirmed by the blockchain. Until the transaction is not confirmed or included in the block it will get cancelled for example if you have set very low fee then your transaction will get cancelled automatically after some time as no miner will included it in their block.

Well said but i would like to clarify that theres no cancelation of your transaction if you do set out very low fee.Its still broadcasted on the network but
due to low fee it would have the tendency or chances that it will got stuck or wont confirm at all yet it wont be pushed by miners but on the current condition
theres no problem with fee though yet they are on the lowest possible amount.

Ya you are right that right now the fees is low but in past when the fees was high that time if you have set very low fee then it can cancelled automatically after some time/days. As it is not broadcasted by any miner. I have experienced this as once in that time i had set low fee and was waited for more then a week for my transaction to get cancelled and then i got my coins back in my wallet.

the situation is still good because the money goes back to your wallet. what if the money comes from the exchange and you are sending your money to another exchange. and it got unconfirmed for a week. what is the next step for this? does anybody here experienced such situation from an exchange? and how did you approach that situation?

I like what you said here. Frightening to the average person but it's true. If you are not a real crypto user and a crypto user told you about this thing, you will hesitate to use crypto because of this aspect. But once you get oriented with crypto, you should know how to double check, triple check your transactions before pressing the confirm button.

We cant reverse and cancel bitcoin transactoin but can force the transaction to be tag as double spent and make transactoin either canceled by the blockchain and refund from the sender,

of course not, it can be reverse or cancel, because as we know that bitcoin is irrevesible transaction, when you submit transaction and listed on blockchain, you will never cancel it or reverse it automatically, the manual way is sending back manual from receiver address

There is no way to reverse bitcoin transaction but you can be able to see it how it was being done because it is recorded in a block chain technology. So, if you will going to have some adjustments to be made then you can do it by getting the copy of the transactions and then make another transactions to justify if it is the lack of funds being forwarded or if the other party should make a refund.

However, it is difficult to address a problem is the transaction done in a wrong address and that would be really a problem because we can't identify the owner of the address so that one can request to the receipient about it and to send it back.

I don't think it is possible for one to cancel or reverse as the case maybe Bitcoin transaction before and after first comfirmation or after. And you have to careful of whoever promise you such services for there are scam site everywhere looking for who they will milk his or her money in the name of trying to helping you.

a several hours of waiting is not normal anymore , how much more if its over a day or two but in your case its been already a week and you dont recieve your funds  .  better if you can contact the support of the exhange that you are using of you can use some kind of accelerator service  online  . that is what i do if one of of my transactions have been stuck for a longer time  .  and if im not mistaken there is also a service or a wallet/exchange that allows you to put extra fees or to modify the fees of your previous transaction ( the unconfirmed one ) because you maybe putting a verry small fee in which miners ignore it  .

 Yeah sometimes it's a scammer or a phishing site that gets people but most of the time it's their own carelessness. We should understand that already that before we make the final send, we have to make sure we placed the correct information first. It's a one miss you die deal 😛

Once your bitcoin transaction has been send into blockchain explorer, it cannot be cancel anymore. But if you made a transaction in the exchange site platform without confirming it to your email or 2FA You can still cancel it as long as your not submitting a confirmation whether to your email or security code.

If you are sending the transaction from blockchain, immediately you click the send button , I do not think it's possible to reverse or cancel the transaction again .
This is because once the send button is clicked on, it sends signal for the coins to be mined.
And there's no way of getting messages across to miners not to mine that particular transaction .

There is nothing we could do once we already sent it even if it is not yet confirmed .
That is why we need to make sure that every time that we would make a transaction the address is correct we should always double check it before we send our money.
I don't really think that there would be something like reverse or cancel bitcoin transaction even in the future .

The very first step in cancelling the bitcoin transaction is to check whether or not it has been confirmed. If the transaction has a conversation, you can’t cancel the transaction as confirmed transactions are irreversible and permanent.
However, if the number of transactions is zero, you can cancel it. There are two different methods on how to cancel your bitcoin transactions.

• RBF (Replace by Fee)
  Double Spending by Setting a Higher Fee

Some wallets support the RBF protocol that allows you to replace the original transaction with a new one with a higher transaction fee. This’d effectively undo the operation.
However, if you want to use this feature, you'd need to make the original transaction replaceable. 
If you cannot use RBF, you may still be able to cancel your Bitcoin transaction by doubling your expenses with higher fees. To do this, make a new transaction equal to the amount of the original transaction and send it to yourself. Make sure the transaction fees are significantly higher than you originally paid.
You may need to use another portfolio or specialized software to double the transaction costs and distribute them over the network. If all goes well, the miners will pick up the new transaction, and your Bitcoin will return to your wallet. Most miners and portfolios, however, have guarantees against double spending, so it is still very likely that this method does not work.         

The only time someone is able to get funds back from a hacker is if they find out a transaction was sent right after it happened and they try to out compete that tx with a really high fee to incentivize the miners

Exactly you are right mate that if we make any transactions with Bitcoin then it’s impossible to cancel it. But I've heard from my friend that if transaction is not confirmed then there have some way but I dont know how to do it.

Yup as long as rhe transaction is not successful it can be,but if done then nothing we can do and it was explained few post above us

Is it really possible?well atleast there are still chance to recover when hack though its very isolated cases and will only happen once in a blue moon

No, that is not possible for sure. You have to be really careful with the clicks you do, especially when you are trying to trade something and convert it in real cash. One of the mistakes that I've heard is sending bitcoin to an eth wallet. If you do this, your funds will get lost since the address is not appropriate. No man can benefit from that move.

Sometimes you wouldn't have the option to outcompete the transactions because there won't be any option for you to do that and transaction fees are automatic. I don' think there's really any solid run-around for making such mistakes so you just have to be very careful.

You know there was a time I actually have it a thought. It's on the blockchain for all to see and once the transaction goes, there are lots of things involved. For example the miners, once you send a transaction, the miners nodes pick it up and it's lined to its receiver. If you want to cancelled , does that mean the miners would refund you? So many things to think about all made me to believe it's impossible. So whichever errors you made in your transaction, don't make in next one.

No, because in my opinion although using the double shopping method to cancel it is not possible because it will definitely be processed quickly one by one and cannot be canceled. and of course when we cancel it requires a process but the bitcoin transaction continues.
the solution is we must be careful before doing something not random.

Notify each user that it cannot be reversed, so you have to be aware, once confirmed, will not return and do not regret completion. If the transaction has been confirmed, you cannot refund work.

In my experience once you transact there is no way for you to cancel that is why there is a notice before you proceed that you check the Bitcoin address many times to make sure it is correct before proceeding.

I do think that some sites will give you another message if you are sure about the transaction, some sites will give you 5 seconds before the transaction goes in if there will be a mistake that you need to correct but I don't think that there has been a site that can cancel your Bitcoin transaction, it is not allowed since the function would likely be abused if given a chance, this is disabled so that there would lesser scams that would happen.

That's not able to do, and also this is also the deficiency about bitcoin transaction.
The verification of doing transaction is still lack and hope it will improve in the future

Surprisingly, it turned out that my instinct did not let me down, and I managed to reset the BSV in time before the Binance their delisting.

Yes, you are lucky! With such abilities you could try to become an expert on the taklimakan platform

have not heard of such a site. What is their specific work?

Taklimakan is a social network. It was created to help users more easily obtain information and analysis of the crypto market and improve their understanding of how the blockchain works. But also if you are ready and competent to share your knowledge, the platform supports such activity

I haven't seen or heard of bitcoin transaction being cancelled or reversed before. Infact to me this is impossible thus we have to be careful with all transactions we make because once initiated, it cannot be cancelled or reversed.

I still haven't heard or seen anything like that could happen in the blockchain, but I think it has been done with the EOS blockchain if I were not mistaken.

One of the things that caught my attention about irreversible transaction which do Bitcoin have thats why im hooked into crypto due to this feature that no fiat/banking system can give out.
Before you do jump into Bitcoin/Crypto World you would surely know this stuff on early phase. Bitcoin tx wont really be reversible thats why making transactions or sending out
funds into other wallet,make it sure that you have entered the right one.

so far, for transactions using bitcoin cannot be canceled. transactions using bitcoin are very fast, accurate and real-time. so, if the transaction process has been carried out, we cannot cancel if an error has occurred. so, we must be careful when doing transactions.
 

No. But you can if you are using wallets that have a regulations. Some wallets today have that feature and its great to have that but when you are on Blockchain wallet reversing transaction will be impossible because it is made directly on the blockchain and even the system cannot reverse it.

yes, as far as I know, it can't stop transactions that you have done on bitcoin, or other altcoins. even this applies to fiat. when you have sent money to someone, it is very difficult to make it back, or cancel it.

the question was very tricky just as it covered merchant interest.
when you use fiat refund is a common thing but crypto doesn't have such option.
So, I guess merchants will just have to initiate a new transaction. So, it must have a special system for setting a unique purchase ID and link it to tx id of the payment.

I know that you could not cancel your bitcoin transaction once you confirmed or accept it because it will be delivered instantly, but if you have a slow internet connection the funds that you have send will be cancelled.

If transaction is still in the mempool you need to check first  where it is in the queue.You can quickly find it  if you write txid in the search field of this service. If its number in line provides sufficient time to complete RBF do it as has been suggested above.

You can cancel only that transaction which is unconfirmed but if the transaction has been made you cannot cancel it or revert it.There are some tricks which you can apply before the transaction is conformed.You can find it on this forum about it.

Bitcoin transaction cannot be cancelled or reversed. The moment  you made a transaction and click send there is no turning back so always make sure before you send. Though there are some newbies who are saying they can cancel the transaction but actually it is before you send it. The web host site will ask a question if you are really sure to continue your transaction and at that time you can cancel it but if you confirm to send then there is no turning back.

Hope this helps.

Well, we can really cancel a bitcoin transaction, more precisely, we cancel it before we have final confirmation, but if we have passed this step as you say, the transaction will continue until it is completed and of course, if we send the wrong address, the opportunity to get the money back is almost zero. Honestly, this is one thing I don't like when using bitcoin, if bitcoin can improve this issue, I believe that bitcoin's position in the community will rise to a higher position.

It is not possible to cancel the transaction that has been done, unless you enter a fee that is less then your transaction is automatically canceled and asked for a larger fee.
Or you can use the trick given by mocacinno, as follows

I think it cannot be cancel or stop ,but it has a chance to stop,if your fee was too low or not suitable in blockchain it will automatically stop, but in manual stop i dont think that it can be.

as ı know you cant reverse or cancel after you confirm bitcoin or any other blockchain transaction, thats why people afraid to use blockchain, because at central money transfer systems you can cancel or change transactıon after confirmation,