Guys, I made a mistake today which I never made before and later noticed that there thousands of transaction which are still stuck in the mempool.
The question is With the simultaneous increase in the numbers of unconfirmed bitcoin transaction today, is there a way to stop an unconfirmed transaction sent using electrum wallet while the "Use Replace-By-Fee" was not set?
Well, yes. You'll need to use the private keys that are associated with that transaction/input that is currently unconfirmed, and sign another transaction, (with a higher fee.)
I don't think you can do this with your electrum client, as they don't really appreciate of people doing this, but you can either do it manually, or use one of the many scripts online.
Haven't tried it myself, but i'm pretty sure you can create a tx with
https://coinb.in/#newTransaction , then sign it with the privkey, and broadcast it, and hope that nodes will add it to the mempool (since it's a doublespend, some nodes might find it conflicting.)
Make sure to do it offline/safe environment.
If you have Bitcoin core synced, you can try this;
2. Double-Spend (harder)
Use -zapwallettxes=1 as Bitcoin Core startup argument.
Use CoinControl (enable it via Bitcoin-Qt settings)
Select your "blocked" input (1KDcKTBTLWnLUED6yMA4Huj5CfzgKfuvJF from 7aa1366669c3c836d7bf7abbc9b934af62bf669a250b66ccd2d72197aeafee35 0.0995BTC) in CoinControl and do a new transaction
Not sure how accurate this information still is, or if it ever worked. Worth a try though.
Same goes for an article that gives a solution for electrum. Not sure how reliable it still is and whatever it could potentially mess up. Make a backup and use @ your own risk.
https://steemit.com/bitcoin/@profitgenerator/tutorial-how-to-fix-unconfirmed-transactions
Perhaps you should wait a bit for more replies, as i'm pretty sure there are some other people here who can give you a more in-depth guide that 100% works.
Normally no, unless you're pool owner or solo miner with huge hashrate where you can create and insert an transaction into your mined block which makes your previously unconfirmed transaction become invalid.
I've seen few people recommend create a transaction with very high fees which conflict with an unconfirmed transaction, but i don't know how reliable is that method.
Can't you doublespend? I don't think his transaction is confirmed.