How do I double spend using electrum for fix unconfirmed transaction

I have two wallets.(Both of them are mine)
Some days ago i did a big mistake.
I sent 1100$ From wallet #1 to wallet #2. (10.0 sat/vB > As you see this is very very low) (TX LINK)
And i sent that 1100$ to my friend from wallet #2 after the transaction upper immediately. (99.3 sat/vB) (TX LINK)
Because of low fee in first transaction, both transactions have n’t confirmed yet.
I asked people to fix these unconfirmed transactions.
They told me use another wallet like Electrum wallet and double spend those unconfirmed transactions.
So i installed Electrum in my windows 7 os.
For double spend using electrum i found this link :
But it seems it has deprecated.
I could n’t understand one part of this tutorial :

Re-create the transaction, but this time put a higher fee.
Sign your transaction, and save it to a file, it should end with .txn extension

My questions :

  1. As you know Blockchain.Com has no RBF option. So those two transactions have n’t RBF flag.
    In this situation can i use double spend with electrum?
  2. How can i create a transaction in offline mode and sign and save it?
    I tried it.But after setting fee and click send button electrum tried to broadcast.And i could n’t find an option for sign or save transaction with .txn ex.
    Would you please share a complete step by step tut about this.
  3. If i double spend first transaction what happen to second unconfirmed one? (I am a bit confused about this)
  4. Should i double spend two unconfirmed transactions with two temp wallets in electrum or double send of first one is enough?

Prepare transaction with multiple recipient

Do you think it is possible programmaticall prepare a Bitcoin transaction that has multiple recipient to send the amount to?

Do you think I can show this trasaction in QR code, so payer can scan it with any of the available wallet app?

transaction fees – How to handle accounts balances

My goal is to manage a huge group of people investments.

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let say each month each one puts in a different amount of dollars (it may even be 1 $) and I need to send to his wallet that amount in bitcoin.

If I’ll send to each person his own share of bitcoin, I’ll lose a lot of money because of fees, there are a lot of micro transactions.

is there any suggestions how I can manage this the best way?

When you come to think about it, any chance it’s similar to how stock exchanges dealing with managing accounts balances? no way they are paying the bitcoin transfer fee on each transaction inside the exchange. it’s not sustainable.

1) I thought about maybe purchasing the bitcoin in bulk, and save it, and to write each account balance in my own ledger, that way each user doesn’t really have a wallet.

pros: no transactions fees.

cons: user doesn’t really have a wallet, I’m fully in charge of his money in case his getting hacked.
How does the exchanges handle keeping all that crypto assets??

  1. I thought about creating each user a wallet, but it means I can’t support small investments.

I’d love some help here.

BlockChain.Com Wallet – Why transaction FEE Is very HIGH

I have two wallets in BlockChain.Com web site.
When i want to transfer bitcoin from one of them situation is like this :

Money for transfer : $1000
Transaction Fee = Priority = $26

In another wallet situation is like this :

Money for transfer : $1000
Transaction Fee = Priority = $210

I am so confused!!!!!!!!!!!!!
Why does BlockChain.Com act like this?
How can i reduce second wallet’s fee?

sql server – Reduce transaction log file utilisation

I have a SQL Server 2017 database that currently has an 80GB data file and a 90GB log file. I want to get the log file down to a more manageable size, because I am about to run some big scripts which will hit the log file hard. The database is also replicated to another database.

If I run dbcc sqlperf('LOGSPACE') then it tells me that utilisation of the log file sits at 99%, and this is preventing me from shrinking the log file down to a more manageable size. For instance, if I run dbcc shrinkfile(mydb_log, 4096) then the error is Cannot shrink log file 2 (mydb_log) because of minimum log space required.

I have tried backing up the database then backing up the transaction log, in full recovery mode. I have tried switching to simple recovery mode, then backing up the database then shrinking the database, but the log file utilisation still sits at 99%.

Does anyone have any suggestions as to what to try next? Is replication likely to be causing an issue? The databases currently sit on a test system, so I can take more extreme measures than if they were in production.

transaction – Consistency of data between two databases on different server

I have to guarantee consistency of data stored in two databases installed on different servers.
The first one is a MySql database and the second is a Sql Server database.

Data’s properties are not the same. There’s only one field that allows me to join them.
Basically, I get the object A in the SqlServer database and retrieve the object B in the MySql database using a where clause A.Id = B.A_Id.

Primary keys are auto generated and INT(11) type. The Sql Server database is not yet implemented.

The connection at the MySql database is managed by a WPF application and the connection at the Sql Server database is managed by a WebAPI. I’m using the ORM NHibernate to perform databases handling.

I have to ensure that no errors occurs during an insert.
I have to insert the object A in the Sql Server database to be able to set the A_Id property of my object B before inserting it.
If the insertion in the MySql database fails, I have to rollback the insertion in the Sql Server database.

I would like to find a solution to avoid an insert/delete in the Sql Server database.
What is the best approach to achieve this ?

I try to implement something like this but I’m facing an issue with the primary key of object A:

Connection open for SqlServer database
Begin transaction
Insert A -> Id is not set : Is it possible to ask NHibernate to book an id here ???
Connection open for MySql database
Begin transaction
Insert B
Commit transaction for B
Commit transaction for A
Close transaction for B
Close transaction for A
Close connection for B
Close connection for A

Thanks in advance.

Bitcoin Transaction Fees When Buying and Selling

Bitcoin not related to fiat currency, I don’t know which wallet you’re using but its really of the exchanger.

I guess you’re using which is not recommend.

Find another wallet to store your bitcoin and exchange your bitcoin locally or using person-to-person trade.


To follow on with a few more question, could you please expand. 1)
When you say “Bitcoin not related to fiat currency” what do you mean?
2) “I guess you’re using which is not recommended” – I
initially tried with those guys but their website was appaling so
couldn’t even verify my identity. So no. But out of interest, why are
they not recommended? 3) Re. “find another wallet”, would you
recommend a wallet that sits on my computer, or phone, and what is the
best method for P2P exchange? How to go about it? –

i’m not fluent in english but i’ll try my best!

1- Bitcoin not related to fiat currency, I thought you were talking about bitcoin core and transactions fee. which is not possible to lose bitcoins or even turning your bitcoins to any fiat currency.

2- coinbase isn’t recommended because they don’t provides full access to bitcoins. its just like PayPal. Your bitcoins in there are just bunch of numbers. And they are custodial Bitcoin wallet.

3- I recommend you to install Bitcoin-core from but if you don’t want to download the whole blockchain(145 GB) and your usage for bitcoin is just simple. You can use they are non-custodial bitcoin wallet and gives you full access to your bitcoins , nobody can track your account and no verification needed.


python – Reading and analyzing budget and transaction data from user input and .csv

Good first effort!

On currentBudget:

One of the things that is easy to tell you about is Python’s context managers docs.

The context manager lets you write code in a different context and takes care of preparing that context and cleaning it up. In your case, there’s a context to deal with opened files 🙂

So, instead of

def currentBudget():
    fileTransaction = open("transactions.csv", "r")
    info = fileTransaction.readlines()
    # ...

it is recommended that you do

def currentBudget():
    with open("transactions.csv", "r") as f:
        info = fileTransaction.readlines()
    # ...

The context manager makes sure the file is properly closed even if the code raises an error.
Generally, inside the with statement you write the least amount of code possible, so that the context can get cleaned up ASAP.

Also, if you are dealing with csv files you might want to take a look at the csv library Python provides: csv docs.

On organisation:

I really liked that you grouped related prints in functions to call repeatedly! One thing you might consider is factoring the different actions you take, depending on the userInput variable, into separate functions. That way, the body of your main function is cleaner and easier to read, and then you have a separate function for each functionality.

On user input:

Clever usage of .lower() to handle capitalised input 😉

You are doing relatively basic I/O, with the user just typing a single letter to pick an action. One thing you might want to do is

userInput = input("nEnter your Choice: ").trim().lower()

This removes leading/trailing whitespace (with .trim).
Additionally, you may want to also add (0) at the end of the line if it is acceptable for the user to write a whole word but you only need to use the first letter to distinguish. This doesn’t make much sense while the actions are a), b), etc, but would make sense if you renamed the options to reflect what they actually do.

Good luck 🙂

privacy – Can lightning transaction participants link the transaction to on-chain funding transaction UTXOs?

Let us start with the direct payment via channel Uab. According to BOLT 02, the payment is conducted by adding an HTLC and settling it. From a protocol perspective, Bob does not know if the payment was originated by Alice. Of course, as there was originally an invoice issued by Bob (and potentially presented out-of-band to Alice), he could deduce that Alice was the payer, but Alice might have forwarded the invoice to someone else who later routed through Alice. Thus, Bob cannot tell with certainty who paid him. All he knows is that he got money from Alice.

In that specific setting, Alice can however be sure that Bob is the one receiving the money as Bob issued the invoice. Invoices are signed by the private key corresponding to the node id, so Alice knows that Bob has requested the payment. Of course, Bob might have been a proxy in the sense that he issued an invoice with the same payment hash as someone else. In that case, Bob might have routed the payment before he was able to present the preimage. Such behavior would be impossible to distinguish for Alice.

Similarly, in the Alice-Isidore-Bob setting: Isidore only knows that Alice sent him money and that he was asked to forward to Bob. Isidore does not know if Alice is the originator nor if Bob is the final destination (this of course assumes the protocol is secure and no attacks exist that reveal such information). Like before, Bob only knows that the payment came through the channel Uib, but cannot tell with certainty who paid him.

In the Alice-Isidore-Bob setting, Alice is aware of all funding transactions as she chose the route and the route is encoded with short_channel_ids which point to funding transactions. Alice will most likely have learnt about them via the gossip protocol.

Litecoin Fork Compilation Validation Error bad-cb-length, Transaction check failed

I have been working on a fork of Bitcoin/Litecoin, and was able to run sudo make && sudo make install with no issues. However when I run kangrocoind (kangrocoin is name of coin), it will begin to boot and load the wallet, however I then receive this error (genesis and merkle shortened for convenience, each one is 64 characters in length):

ERROR: ConnectBlock: Consensus::CheckBlock: bad-cb-length, Transaction check failed (tx hash 2dce389…) (code 16)
2021-04-11T00:09:47Z InvalidChainFound: invalid block=1a59bed… height=0 log2_work=20.000022 date=2021-04-10T01:21:50Z
kangrocoind: validation.cpp:1294: void InvalidChainFound(CBlockIndex*): Assertion `tip’ failed.

Does anyone know a possible solution? Thanks!