Hello,

I have executed a transaction from Wallet A (Bitcoin Core) to Wallet B in early 2018 (my block chain was 3 years behind at that time).

The amount has never been credited to Wallet B. After research at blockchain.info the transaction ID (0 transaction confirmations) is not available and the exact amount is still assigned to Wallet A. Only my credit there does not show this sent amount.

Since my blockchain hasn't been updated since then and is therefore almost 5 years in behind, I would like to know what happens if I run the update? Would the transaction still be executed or not? Would there be a way to cancel the transaction?

Thanks a lot.

Wallet update is not going to affect the blockchain. A blockchain is keeping the record of all transaction which do not have any connection with any wallet client.

What I understand from reading you post is that your core wallet never sent the coin to your blockchain wallet hence the coin never reached there and it was always in the core wallet. If you know the address of the coin then use any block explorer and see it's there.

PS: I am assuming that you have not sent the coins to a wrong address since you said the coins were there (core).

Not sure after reading LoyceV's response but my basic instinct is saying that you should be safe. I do not see any reason for a client to start broadcasting a tx that was made long time ago and never was broadcasted.

Do you know the private key of the wallet? Assuming you do. In that case try to restore the wallet using Electrum and once you see the balance then send them to another wallet (fees are too high right now which sucks by the way). So once the address is empty (make sure the tx has minimum 1 confirmation), then try to restore the wallet using your core client. This is the safest practice I can think off now.

PS: Make sure you have verified the signature of the downloaded Electrum client. Here is a tutorial if needed : https://bitcoinelectrum.com/how-to-verify-your-electrum-download/

Edit:
The reason is that the client has not synchronized in full yet.

Thank you for your help so far.

Yes, I have the private key. And my wallet.dat on my pc. I don't understand why I should restore this wallet and make another transaction. Sorry, but could you explain this for a 5 year old? Thank you.

PS: Wallet B is a litbit.eu online wallet

My goal is it to cancel the tx and store the BTC on a more safer place than wallet B

I don't think the command written in that thread works. Must add quotation marks at the start and end of the file path.
The command must be as follows.

Ledger or Trezor hardware wallet is probably the easiest and most n00b friendly.

After moving your Bitcoin, you may want to check for Forkcoins you own. As always on crypto: don't do anything before you understand what you're doing.

Good to hear the good news renner123.

Now about storing safely, I will suggest the same as BitMaxz in the post above but with some additional security step. However a hardware wallet is easier if you find it hard of course.

You will need two devices. One will never go online that will have your wallet stored. You can write up the seeds and always delete the wallet after making a transaction on the offline device if this was being used for any other task by any other family member but make sure this never goes online. In the online device you will have a watch only wallet using the master public key of the wallet from offline device.

Whenever you will need to broadcast a transaction:
- You will create the tx from the online device then export the file.
- Using a USB stick or other removable disk take the file and from the offline device load the tx and sign it. Then export the signed tx and save it in the removable disk.
- Load the signed tx in the online device, online watch only wallet and broadcast the tx.

This way your wallet is never going online and you have zero risk of getting caught by any malware or hacking of your wallet.

In the offline device, the balance will show zero always by the way. The reason is - it was never online and was never been able to sync with the blockchain. You will always see the up to date data in the watch only device by the way.

And please do not skip this step before installing the software. @renner123