I downloaded Bitcoin Core (64 bit) and I am still waiting for it to synchronize. But just now, when I open the software, it loads from 1% to 100% and then a message appears with the inscription

Cannot obtain a lock on data directory C:/Users/ADMIN/AppData/Roaming/Bitcoin. Bitcoin Core is probably already running.

Then the program disappears to the task bar and I can't open it from the task bar. Please, any help?

  • when I try to open the software it says " cannot obtain a lock on data directory C:/Users/ADMIN/AppData/Roaming/Bitcoin.Bitcoin Core is probably already running"
    – pearl
    Commented Jun 28, 2015 at 17:32

2 Answers 2


Try opening your data directory and deleting the file .lock

Make sure Bitcoin is closed while you're doing this.

  • 2
    please, i deleted the .lock and after re-launching the bitcoin core software the same problem exist. It loads from 1% to 100% and after it is done loading it disappears. But I realize the .lock file which I deleted is restored after software was launched. This is really giving me headache pls help me
    – pearl
    Commented Jun 29, 2015 at 7:54
  • Nick, please help me !!!
    – pearl
    Commented Jun 29, 2015 at 15:55
  • Right now, another problem has appear. Bitcoin core software has totally freeze at "loading block index" I have 1 BTC on it. Should I forget it ???????
    – pearl
    Commented Jun 29, 2015 at 18:11
  • @pearl: The .lock should be present while Bitcoin Core is running. It ensures that only one instance of the program is being run at the same time. For the new problem, you should create another question post. Please add as much useful details as possible. [Oops, I thought it was this month, not last month.]
    – Murch
    Commented Jul 29, 2015 at 12:09

You must have forcibly shut down the bitcoin client previously, or maybe the daemon is still running and you are attempting to run another client listening at the same port.

To kill all bitcoin client instances, you need to know the processes listening to the port.

Open a command prompt with administrator privileges and type in the following command to get the details of services running

netstat -o

This will list all the services listening to the various ports. Find the one with the bitcoin service (you can also see the port, 8332 for the actual bitcoin client and 18332 for the testnet client). Once you have acquired the process IDs, you need to forcibly kill the processes by typing in the command

Taskkill /PID <process_id_here> /F

Try restarting the client.

Useful links I used as source:


Killing Processes

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