Quote from: stompix on October 18, 2017, 01:26:14 PM

Quote from: Naster on October 18, 2017, 01:20:47 PM

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?

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

Quote from: Naster on October 18, 2017, 01:20:47 PM

So it should be a good idea to discuss this topic.

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However, these threads are outdated, and in some of them, it has not been clearly answered.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

Quote

It is when a person broadcast two seperate transactions which spends the same outputs. Since the majority of the network runs Bitcoin Core, the reference client, they would first receive the first transaction and store it in their mempool. The other transaction will then be rejected. It is fairly hard to attempt to doublespend the transaction on the blockchain but it can be accomplished. If you have a transaction which has low fees, wait till most of the peers drops your transaction in the mempool then you can broadcast it again. Blockchain.info used to have a page to allow people to test it out but it's removed already. There are also some open sourced programs that allows you to double spend but I can't guarantee it is safe since you have to give your private key.

Blockchain.info seems to be rebroadcasting your transaction whenever it gets dropped out of mempool. Get the private key and delete it out from your blockchain.info, store it somewhere safe then wait for a week. After that, verify that it has dropped out of the mempool and import it to a desktop client to send the BTC. That's what I have done before anyway.

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.