Cannot get a provider from IBMQ

Question

My code is:

    from qiskit import IBMQ
    IBMQ.load_account()
    provider = IBMQ.get_provider('ibm-q')
    qcomp = provider.get_backend('ibmq_16_melbourne')

but I run it in Jupyter I get the following message

    QiskitBackendNotFoundError                Traceback 
    (most recent call last)
    <ipython-input-6-f874d37829a9> in <module>
      2 IBMQ.load_account()
      3 provider = IBMQ.get_provider('ibm-q')
    ----> 4 qcomp = 
    provider.get_backend('ibmq_16_melbourne')

                                                                        
 
    ~\anaconda3\lib\sitepackages\qiskit\providers
     \providers\provider.py in get_backend(self, name, 
     **kwargs)
     53             raise 
     QiskitBackendNotFoundError("More than one backend 
     matches the criteria")
     54         if not backends:
     ---> 55             raise 
     QiskitBackendNotFoundError("No backend matches the 
     criteria")
     56 
     57         return backends[0]

     QiskitBackendNotFoundError: 'No backend matches the 
     criteria'

I have already made an account at IBM, and have already seen the post (Trying to get a provider from IBMQ but get 'No provider matches the criteria.'), but the problem still exists.

Answer 1

The backend that you choose ( 'ibmq_16_melbourne' ) was retired recently. With a different backend, it should work. You can find available IBM Quantum systems here.

https://quantum-computing.ibm.com/services?services=systems

Answer 2

As the other answer stated, this is because ibmq_16_melbourne is no longer in service. But in general, to know which backend is in service and available to you, you can quickly run the following script:

from qiskit import IBMQ, Aer
provider = IBMQ.load_account()
available_cloud_backends = provider.backends() 
print('\n Cloud backends:')
for i in available_cloud_backends: print(i)

available_local_backends = Aer.backends() 
print('\n Local backends: ')
for i in available_local_backends: print(i)

This will output something like:

 Cloud backends:
ibmq_qasm_simulator
ibmq_armonk
ibmq_santiago
ibmq_bogota
ibmq_lima
ibmq_belem
ibmq_quito
simulator_statevector
simulator_mps
simulator_extended_stabilizer
simulator_stabilizer
ibmq_manila

 Local backends: 
aer_simulator
aer_simulator_statevector
aer_simulator_density_matrix
aer_simulator_stabilizer
aer_simulator_matrix_product_state
aer_simulator_extended_stabilizer
aer_simulator_unitary
aer_simulator_superop
qasm_simulator
statevector_simulator
unitary_simulator
pulse_simulator

This might save you time from having to look up this info through the IBM Q webpage.