Regression in loading models in release 3.8.12

[mart-r]

How to reproduce the behaviour

I don't know how far this goes exactly, but I've got an en_core_web_md v3.1.0 model saved on disk, and I have this script for loading it:

import spacy
print("spacy==", spacy.__version__)
spacy_path = "en_core_web_md/"
print("Loading Spacy Model")
nlp = spacy.load(spacy_path)
print("NLP:", nlp.meta['name'], "@", nlp.meta['version'])

In spacy==3.8.7 I get:

 % python .temp/2026_03_23_spacy_model_load/load_model.py
spacy== 3.8.7
Loading Spacy Model
/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.venv312/lib/python3.12/site-packages/spacy/util.py:922: UserWarning: [W095] Model 'en_core_web_md' (3.1.0) was trained with spaCy v3.1.0 and may not be 100% compatible with the current version (3.8.7). If you see errors or degraded performance, download a newer compatible model or retrain your custom model with the current spaCy version. For more details and available updates, run: python -m spacy validate
  warnings.warn(warn_msg)
NLP: core_web_md @ 3.1.0

And same in 3.8.11:

 % python .temp/2026_03_23_spacy_model_load/load_model.py
spacy== 3.8.11
Loading Spacy Model
/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py:969: UserWarning: [W095] Model 'en_core_web_md' (3.1.0) was trained with spaCy v3.1.0 and may not be 100% compatible with the current version (3.8.11). If you see errors or degraded performance, download a newer compatible model or retrain your custom model with the current spaCy version. For more details and available updates, run: python -m spacy validate
  warnings.warn(warn_msg)
NLP: core_web_md @ 3.1.0

Yet in spacy==3.8.12 I get:

% python .temp/2026_03_23_spacy_model_load/load_model.py
spacy== 3.8.12
Loading Spacy Model
/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py:969: UserWarning: [W095] Model 'en_core_web_md' (3.1.0) was trained with spaCy v3.1.0 and may not be 100% compatible with the current version (3.8.12). If you see errors or degraded performance, download a newer compatible model or retrain your custom model with the current spaCy version. For more details and available updates, run: python -m spacy validate
  warnings.warn(warn_msg)
Traceback (most recent call last):
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/load_model.py", line 5, in <module>
    nlp = spacy.load(spacy_path)
          ^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/__init__.py", line 52, in load
    return util.load_model(
           ^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 526, in load_model
    return load_model_from_path(Path(name), **kwargs)  # type: ignore[arg-type]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 598, in load_model_from_path
    nlp = load_model_from_config(
          ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 646, in load_model_from_config
    nlp = lang_cls.from_config(
          ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/language.py", line 1832, in from_config
    resolved_nlp = registry.resolve(
                   ^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 760, in resolve
    resolved, _ = cls._make(
                  ^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 809, in _make
    filled, _, resolved = cls._fill(
                          ^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 937, in _fill
    result = schema.parse_obj(validation)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/main.py", line 1370, in parse_obj
    return cls.model_validate(obj)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/main.py", line 716, in model_validate
    return cls.__pydantic_validator__.validate_python(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 100, in __getattr__
    raise PydanticUserError(self._error_message, code=self._code)
pydantic.errors.PydanticUserError: `ConfigSchemaNlp` is not fully defined; you should define `Language`, then call `ConfigSchemaNlp.model_rebuild()`.

For further information visit https://errors.pydantic.dev/2.12/u/class-not-fully-defined

Your Environment

• Operating System: MacOS and ubuntu (on CI)
• Python Version Used: 3.12
• spaCy Version Used: 3.8.12 (the problematic)
• Environment Information: The OLD en_core_web_md model.

PS:
I understand that you guys are probably unable to indefinitely support loading old models. But a regression like this in a patch version seems out of place to me.

PPS:
If I've made some mistake on my end, do point it out.

[mart-r]

I have now tried to see if this affects other models as well and it seems to affect 3.8.0 as well.
I downloaded the latest en_core_web_md (3.8.0) and saved it on disk. Then tried to load it on spacy==3.8.12:

% grep "version" en_core_web_md_3.8.0/meta.json
  "version":"3.8.0",
  "spacy_version":">=3.8.0,<3.9.0",
  "spacy_git_version":"5010fcbd3",
      "name":"ClearNLP Constituent-to-Dependency Conversion",
      "url":"https://github.com/clir/clearnlp-guidelines/blob/master/md/components/dependency_conversion.md",
% python load_model.py
spacy== 3.8.12
Loading Spacy Model from en_core_web_md_3.8.0
Traceback (most recent call last):
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/load_model.py", line 5, in <module>
    nlp = spacy.load(spacy_path)
          ^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/__init__.py", line 52, in load
    return util.load_model(
           ^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 526, in load_model
    return load_model_from_path(Path(name), **kwargs)  # type: ignore[arg-type]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 598, in load_model_from_path
    nlp = load_model_from_config(
          ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 646, in load_model_from_config
    nlp = lang_cls.from_config(
          ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/language.py", line 1832, in from_config
    resolved_nlp = registry.resolve(
                   ^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 760, in resolve
    resolved, _ = cls._make(
                  ^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 809, in _make
    filled, _, resolved = cls._fill(
                          ^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 937, in _fill
    result = schema.parse_obj(validation)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/main.py", line 1370, in parse_obj
    return cls.model_validate(obj)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/main.py", line 716, in model_validate
    return cls.__pydantic_validator__.validate_python(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 100, in __getattr__
    raise PydanticUserError(self._error_message, code=self._code)
pydantic.errors.PydanticUserError: `ConfigSchemaNlp` is not fully defined; you should define `Language`, then call `ConfigSchemaNlp.model_rebuild()`.

For further information visit https://errors.pydantic.dev/2.12/u/class-not-fully-defined

The (slightly) changed script was:

import spacy
print("spacy==", spacy.__version__)
spacy_path = "en_core_web_md_3.8.0"
print("Loading Spacy Model from", spacy_path)
nlp = spacy.load(spacy_path)
print("NLP:", nlp.meta['name'], "@", nlp.meta['version'])

And again, loading off disk works fine on 3.8.11.

[mart-r]

Went a step further and looks like I can't even load the downloaded model:

% python -m spacy download en_core_web_md              
Collecting en-core-web-md==3.8.0
  Using cached https://github.com/explosion/spacy-models/releases/download/en_core_web_md-3.8.0/en_core_web_md-3.8.0-py3-none-any.whl (33.5 MB)
✔ Download and installation successful
You can now load the package via spacy.load('en_core_web_md')
% python -c "import spacy;spacy.load('en_core_web_md')"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/__init__.py", line 52, in load
    return util.load_model(
           ^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 524, in load_model
    return load_model_from_package(name, **kwargs)  # type: ignore[arg-type]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 560, in load_model_from_package
    return cls.load(vocab=vocab, disable=disable, enable=enable, exclude=exclude, config=config)  # type: ignore[attr-defined]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/en_core_web_md/__init__.py", line 10, in load
    return load_model_from_init_py(__file__, **overrides)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 741, in load_model_from_init_py
    return load_model_from_path(
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 598, in load_model_from_path
    nlp = load_model_from_config(
          ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/util.py", line 646, in load_model_from_config
    nlp = lang_cls.from_config(
          ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/spacy/language.py", line 1832, in from_config
    resolved_nlp = registry.resolve(
                   ^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 760, in resolve
    resolved, _ = cls._make(
                  ^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 809, in _make
    filled, _, resolved = cls._fill(
                          ^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/confection/__init__.py", line 937, in _fill
    result = schema.parse_obj(validation)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/main.py", line 1370, in parse_obj
    return cls.model_validate(obj)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/main.py", line 716, in model_validate
    return cls.__pydantic_validator__.validate_python(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/martratas/Documents/CogStack/.MedCAT.nosync/monorepo-nlp/medcat-v2/.temp/2026_03_23_spacy_model_load/.venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 100, in __getattr__
    raise PydanticUserError(self._error_message, code=self._code)
pydantic.errors.PydanticUserError: `ConfigSchemaNlp` is not fully defined; you should define `Language`, then call `ConfigSchemaNlp.model_rebuild()`.

For further information visit https://errors.pydantic.dev/2.12/u/class-not-fully-defined

[honnibal]

Yanking the release. Really sorry about this.

[honnibal]

I think the issue is that I didn't update the confection pin. In testing I tested with the recent confection release and that appeared to work, but spaCy + old confection seems to be broken.

Not 100% sure, investigating now. It's possible just pip install -U confection will work in the meantime.

[honnibal]

Yeah clean installation works fine, but in-place installation was broken as it would leave you with an incompatible confection. Rebuilding now.

[mart-r]

Yeah clean installation works fine, but in-place installation was broken as it would leave you with an incompatible confection. Rebuilding now.

Interestingly when I did a fresh install of spacy==3.8.12 loading failed on python 3.12 and 3.13. I'm on MacOS with M1 so not sure if there's something different in other enviornments. Though I haven't tried 3.14 yet.
I originally saw this issue pop up in our CI, on ubuntu-latest on python 3.11. So it's not only a MacOS issue (or at least wasn't at that point).

It's possible just pip install -U confection will work in the meantime.

On my 3.13 install confection==0.1.5 was installed by default. And pip -U install confection updated to 1.3.2 but that's not actually compatible with spacy==3.8.12:

spacy 3.8.12 requires confection<1.0.0,>=0.0.4, but you have confection 1.3.2 which is incompatible.

I tried just in case anyway but still got the same error.

[mart-r]

Yeah clean installation works fine, but in-place installation was broken as it would leave you with an incompatible confection. Rebuilding now.

For what it's worth, 3.8.13 seems to have resolved this for me.