Remove deprecated `BackendV1` elements, including base class, `providers.models` and `qobj` modules #13793

ElePT · 2025-02-05T18:31:38Z

Summary

This PR builds upon (~~and is BLOCKED BY~~) the changes in #13805.
This PR removes BackendV1 and all related modules and utils. This includes:

from qiskit/providers:
- BackendV1
- BackendV2Converter
- convert_to_target
- BackendPropertyError
- BackendConfigurationError
from qiskit/providers/models: these were BackendV1 data structures. Full module removed
- BackendConfiguration
- BackendProperties
- BackendStatus
- QasmBackendConfiguration
- PulseBackendConfiguration
- UchannelLO
- GateConfig
- PulseDefaults
- Command
- JobStatus
- GateProperties
- Nduv
Removed PulseQobjDef from qiskit/providers/models (this steps a bit into pulse removal realm)
from qiskit/qobj: Full module removed.
- QobjExperimentHeader
- QobjHeader
- QasmQobj
- QasmQobjInstruction
- QasmQobjExperimentConfig
- QasmQobjExperiment
- QasmQobjConfig
- QasmExperimentCalibrations
- GateCalibration
- PulseQobj
- PulseQobjInstruction
- PulseQobjExperimentConfig
- PulseQobjExperiment
- PulseQobjConfig
- QobjMeasurementOption
- PulseLibraryItem

Note that there were two classes defined in the qobj utils (MeasLevel and MeasReturnType) used in the result class, so they have been moved to result/models.py.

TODOs

Reno

Details

What should we do with the "Migrate from BackendV1 to BackendV2" guide? Check with docs team to make sure it's covered somewhere else. -> Update: opened Add Migration guide from BackendV1 to BackendV2 documentation#2705
This removal breaks Aer, currently seen in image tests:

qiskit.exceptions.OptionalDependencyImportWarning: While trying to import 'Qiskit Aer', some components were located but raised other errors during import. You might have an incompatible version installed. Qiskit will continue as if the optional is not available.
module 'qiskit_aer' failed to import with: ImportError("cannot import name 'convert_to_target' from 'qiskit.providers' (/home/vsts/work/1/s/qiskit/providers/__init__.py)")

coveralls · 2025-02-17T15:49:27Z

Pull Request Test Coverage Report for Build 13684630517

Details

29 of 67 (43.28%) changed or added relevant lines in 9 files are covered.
12 unchanged lines in 6 files lost coverage.
Overall coverage increased (+1.1%) to 88.101%

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/visualization/pulse_v2/device_info.py	0	1	0.0%
qiskit/visualization/gate_map.py	0	37	0.0%

Files with Coverage Reduction	New Missed Lines	%
qiskit/pulse/calibration_entries.py	1	83.49%
qiskit/pulse/parameter_manager.py	1	96.97%
qiskit/pulse/schedule.py	1	88.03%
qiskit/utils/deprecate_pulse.py	1	94.12%
crates/circuit/src/circuit_instruction.rs	3	89.46%
crates/qasm2/src/lex.rs	5	91.73%

Totals
Change from base Build 13683975981:	1.1%
Covered Lines:	75167
Relevant Lines:	85319

💛 - Coveralls

qiskit-bot · 2025-02-17T16:14:16Z

One or more of the following people are relevant to this code:

@Eric-Arellano
@abbycross
@beckykd
@enavarro51
@Qiskit/terra-core
@ajavadia
@levbishop
@nkanazawa1989
@t-imamichi

…moval

eliarbel · 2025-03-03T13:09:47Z

Oops, just another qobj_id escape :-) I would remove it:

qiskit/qiskit/providers/__init__.py

Line 606 in 1eb8e5b

'qobj_id': ', '.join(x.name for x in self.circuits),

…into macro-removal

… Remove json decoding utils that weren't part of the public API and flew under the radar in the Fake Backend removal PR.

wshanks · 2025-03-03T23:44:18Z

qiskit/qobj/utils.py

-class MeasReturnType(str, Enum):
-    """PulseQobjConfig meas_return allowed values."""
-
-    AVERAGE = "avg"
-    SINGLE = "single"
-
-
-class MeasLevel(IntEnum):
-    """MeasLevel allowed values."""
-
-    RAW = 0
-    KERNELED = 1
-    CLASSIFIED = 2


Will a warning about the move of these get into 1.4? It might be worth importing these back here from the new location, maybe with a module level __getattr__ to warn about the move since it is close to 2.0 and these are referenced in other packages.

My comment was made assuming MeasLevel and MeasReturnType were still public but I see now that they are in qiskit.result.model and not added to the docs. Are they not intended to be public any more?

Hmm I see. I wasn't aware of the external use of these classes, I treated them as an internal migration. They were not part of the docs, not even in the original location, and they were buried among other outdated utilities so I didn't think they would be used externally. Now taking a closer look, they were probably intended to be public even though they technically weren't. Thanks for pointing this out @wshanks.

See 27c2c63. I added a note specifying the old and new import paths. As for the deprecation warning, it was discussed internally and it is not in scope for an internal API. For external devs, the reno should contain the migration info. For IBM internal devs, I can help migrate. So far I have seen qiskit-experiments and qiskit-ibm-runtime importing these classes, let me know if you are aware of others.

Thanks, @ElePT! I missed the fact that this was always internal before with my previous messages 🤦‍♂️ With the commit you mentioned, you added these classes to qiskit.result but didn't add them to the docs. Will they still be considered private going forward?

I checked qiskit-experiments' usage and it only uses = and == with the enum members so I think we could redefine the enums internally if necessary. I was a little worried about some of the other enum features like in where using two definitions of the enum might not work.

Yes, I confirmed that they will stay private. I think that vendoring them in qiskit-experiments would be a good idea moving forward.

…55) BackendV1 and qiskit.qobj removals in Qiskit/qiskit#13793 cause the test in qiskit_neko/tests/experiments/test_tomography.py to fail. This is part of the tests that are blocking the Qiskit/qiskit#13793 and Qiskit/qiskit#13872 PR in Qiskit from being merged. There is a PR in Qiskit Experiments that address these removals: qiskit-community/qiskit-experiments#1526. Until it is merged, we need to skip this failing test. Tracked in #54

…moval

mtreinish

Overall this LGTM. Thanks for doing this! This finally finishes a process I started back in 2019 with #3383 of trying to clean up these interfaces. I'm glad to see that 4 years later we're finally able to remove this legacy code from Qiskit. This is incredibly satisfying to see.

I just had a couple small comments inline. I thinkt he only one that needs an update is the release notes one though.

mtreinish · 2025-03-05T18:07:12Z

qiskit/providers/__init__.py

@@ -21,7 +21,7 @@
 provider is anything that provides an external service to Qiskit. The typical
 example of this is a Backend provider which provides
 :class:`~qiskit.providers.Backend` objects which can be used for executing
-:class:`~qiskit.circuit.QuantumCircuit` and/or :class:`~qiskit.pulse.Schedule`


This PR doesn't remove schedules yet but it's fine. :)

mtreinish · 2025-03-05T18:16:05Z

qiskit/providers/backend.py

-    If migrating a provider from :class:`~qiskit.providers.BackendV1`
-    one thing to keep in mind is for
-    backwards compatibility you might need to add a configuration method that
-    will build a :class:`~qiskit.providers.models.BackendConfiguration` object
-    and :class:`~qiskit.providers.models.BackendProperties` from the attributes
-    defined in this class for backwards compatibility.


We could have left this comment in the docstring because someone could conceivably be migrating from BackendV1 post removal (as part of fixing 2.0 compatibility). But it also is fine to remove it since this lives in the 1.4 docs.

mtreinish · 2025-03-05T18:45:48Z

qiskit/visualization/bloch.py

@@ -138,7 +138,7 @@ def draw(self, renderer):

 class Bloch:
    """Class for plotting data on the Bloch sphere.  Valid data can be
-    either points, vectors, or qobj objects.


lol, what!? There is nothing that ever took a qobj here afaik.

mtreinish · 2025-03-05T18:49:16Z

releasenotes/notes/remove-backend-v1-et-al-cccd8f6b71a97ffc.yaml

+    The ``BackendV1`` model has been removed following its deprecation in 
+    Qiskit 1.2.0. This includes the ``BackendV1`` class as well as related
+    modules and utils, as they have been superseded by the :class:`.BackendV2` 
+    model. The list of removed items includes:


You might want to mention this also includes things that previously could accept a backend v1 object like generate_preset_pass_manager etc.

mtreinish · 2025-03-05T18:51:06Z

releasenotes/notes/remove-backend-v1-et-al-cccd8f6b71a97ffc.yaml

+      legacy ``BackendV1`` components (such as ``BackendConfiguration`` or ``BackendProperties``)
+
+    * ``BackendPropertyError`` and ``BackendConfigurationError``: exceptions linked to removed classes
+


I think there are a couple of removals missing here. The ones I caught are:

Target.from_configuration() backend_properties` arg

target_to_backend_properties

I might have missed others though.

mtreinish

LGTM, thanks for the quick update.

ElePT force-pushed the macro-removal branch from 7d6eb5e to ab1fa67 Compare February 5, 2025 19:01

This was referenced Feb 6, 2025

Remove pulse-related passes #13798

Merged

Remove fake backends based on BackendV1 and related tools #13805

Merged

ElePT force-pushed the macro-removal branch from ab1fa67 to 7c208de Compare February 17, 2025 15:24

ElePT changed the title ~~[WIP] Remove deprecated qobj, pulse module, and related tools from BackendV1~~ [WIP] Remove deprecated BackendV1 elements, including base class, providers.models and qobj modules Feb 17, 2025

ElePT added the on hold Can not fix yet label Feb 17, 2025

ElePT force-pushed the macro-removal branch from 7c208de to 935892b Compare February 17, 2025 16:11

ElePT changed the title ~~[WIP] Remove deprecated BackendV1 elements, including base class, providers.models and qobj modules~~ Remove deprecated BackendV1 elements, including base class, providers.models and qobj modules Feb 17, 2025

ElePT marked this pull request as ready for review February 17, 2025 16:14

ElePT requested review from a team, nonhermitian, eggerdj, wshanks, nkanazawa1989 and jyu00 as code owners February 17, 2025 16:14

ElePT added this to the 2.0.0 milestone Feb 17, 2025

eliarbel mentioned this pull request Feb 18, 2025

Remove pulse module files, pulse visualization and final cleanup #13872

Merged

1ucian0 assigned eliarbel and ElePT Feb 20, 2025

This was linked to issues Feb 24, 2025

Remove BackendV1 and related dependencies, deprecated in 1.2 #13708

Closed

Remove qobj, deprecated in 1.2 #13701

Closed

Remove BackendV1, converters, models, qobj and update tests.

b9c862f

ElePT force-pushed the macro-removal branch from 935892b to b9c862f Compare February 28, 2025 15:19

ElePT added 2 commits March 3, 2025 09:19

Merge branch 'main' of https://github.com/Qiskit/qiskit into macro-re…

488a1b2

…moval

Add reno

e7c984f

ElePT force-pushed the macro-removal branch from 033ae63 to e7c984f Compare March 3, 2025 09:59

ElePT removed the on hold Can not fix yet label Mar 3, 2025

ElePT and others added 4 commits March 3, 2025 14:13

Update __init__.py

de002a8

Remove unused import

71170ee

Merge branch 'macro-removal' of https://github.com/ElePT/qiskit-terra …

296da82

…into macro-removal

Remove remaining qobj references (including test names and comments).…

134a22d

… Remove json decoding utils that weren't part of the public API and flew under the radar in the Fake Backend removal PR.

wshanks reviewed Mar 3, 2025

View reviewed changes

eliarbel mentioned this pull request Mar 4, 2025

Remove references to BackendV1 following its removal in Qiskit 2.0 qiskit-community/qiskit-experiments#1525

Closed

Document migration of MeasLevel and MeasReturnType

27c2c63

ElePT force-pushed the macro-removal branch from d11f3a5 to 27c2c63 Compare March 4, 2025 16:34

Mix malformed table

9717823

mtreinish added priority: high Changelog: Removal Include in the Removed section of the changelog labels Mar 4, 2025

ElePT mentioned this pull request Mar 5, 2025

Update use of classes removed in Qiskit 2.0 Qiskit/qiskit-ibm-runtime#2173

Merged

wshanks mentioned this pull request Mar 5, 2025

Prepare for Qiskit 2.0 by addressing removed classes and methods qiskit-community/qiskit-experiments#1526

Merged

eliarbel mentioned this pull request Mar 5, 2025

Skip StateTomography test until Qiskit Experiments is ready for 2.0 Qiskit/qiskit-neko#55

Merged

ElePT mentioned this pull request Mar 5, 2025

Skip qiskit-machine-learning tests until the downstream dependencies are updated to 2.0 Qiskit/qiskit-neko#56

Merged

Merge branch 'main' of https://github.com/Qiskit/qiskit into macro-re…

2467e16

…moval

mtreinish reviewed Mar 5, 2025

View reviewed changes

ElePT and others added 2 commits March 5, 2025 20:41

Apply comments from Matt's review

79a7b66

Merge branch 'main' into macro-removal

79c92be

mtreinish approved these changes Mar 5, 2025

View reviewed changes

mtreinish enabled auto-merge March 5, 2025 20:11

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Merged via the queue into Qiskit:main with commit 9c00a93 Mar 5, 2025
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Remove deprecated `BackendV1` elements, including base class, `providers.models` and `qobj` modules #13793

Remove deprecated `BackendV1` elements, including base class, `providers.models` and `qobj` modules #13793

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		legacy ``BackendV1`` components (such as ``BackendConfiguration`` or ``BackendProperties``)

		* ``BackendPropertyError`` and ``BackendConfigurationError``: exceptions linked to removed classes

Remove deprecated BackendV1 elements, including base class, providers.models and qobj modules #13793

Remove deprecated BackendV1 elements, including base class, providers.models and qobj modules #13793

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ElePT commented Feb 5, 2025 • edited Loading

Summary

TODOs

Details

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Pull Request Test Coverage Report for Build 13684630517

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Remove deprecated `BackendV1` elements, including base class, `providers.models` and `qobj` modules #13793

Remove deprecated `BackendV1` elements, including base class, `providers.models` and `qobj` modules #13793

ElePT commented Feb 5, 2025 •

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coveralls commented Feb 17, 2025 •

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