I'm trying to use QiskitRuntimeService() and start a session to find the expectation value of some operator but I keep getting this error:

ApiException: Error: Provided API key could not be found., Code: 400.

The line that gives me the error is:

service = QiskitRuntimeService()

How can I fix it?


1 Answer 1


You have to initialize your account before you can start using Qiskit Runtime. If you don't have the credentials saved in your disk, you can initialize a QiskitRuntimeService instance as follows:

from qiskit_ibm_runtime import QiskitRuntimeService

# Save an IBM Cloud account on disk
token = '***'  # <== Use your token here
QiskitRuntimeService.save_account(channel="ibm_quantum", token=token)

You can find the token in your IBM Quantum account page.

If the error keeps happening, try to delete the saved account from disk at first then save it again:

QiskitRuntimeService.save_account(channel="ibm_quantum", token=token, overwrite=True)

Once the credentials are saved, you can initialize the QiskitRuntimeService instance without passing any parameters:

# Read default credentials from disk
service = QiskitRuntimeService()

For more details see here.

  • $\begingroup$ I already did that, but it still won't work. I also tried to regenerate my token but I got the same error every time. $\endgroup$
    – user184655
    Mar 16, 2023 at 19:43
  • $\begingroup$ Did you try to add overwrite=True when calling with the new token? $\endgroup$ Mar 16, 2023 at 20:28
  • $\begingroup$ Yes, I did that too. $\endgroup$
    – user184655
    Mar 17, 2023 at 2:01
  • $\begingroup$ I actually get two different error. One of them is the one I mentioned and the other error is: IBMNotAuthorizedError: '401 Client Error: Unauthorized for url: auth.quantum-computing.ibm.com/api/users/loginWithToken. Login failed., Error code: 3446.' $\endgroup$
    – user184655
    Mar 17, 2023 at 3:35
  • $\begingroup$ Try to delete the saved account from disk at first: QiskitRuntimeService.delete_account(). $\endgroup$ Mar 17, 2023 at 6:06

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