HTML conversion fails with nbformat 5.5.0

[holl-]

Since the release of nbformat 5.5.0, the conversion of this notebook fails on GitHub Actions.
We have reverted to 5.4.0, which works correctly.
This is the error log with 5.5.0:

[NbConvertApp] Converting notebook docs/Math_Introduction.ipynb to html
[NbConvertApp] ERROR | Notebook JSON is invalid: data.cells[{data__cells_x}] must be valid exactly by one definition (0 matches found)

Failed validating <unset> in notebook['data']['cells']:

On instance:
<unset>
[NbConvertApp] ERROR | Notebook is invalid after preprocessor <nbconvert.preprocessors.tagremove.TagRemovePreprocessor object at 0x7f086ea7f460>
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.8.13/x64/bin/jupyter-nbconvert", line 8, in <module>
    sys.exit(main())
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/jupyter_core/application.py", line 269, in launch_instance
    return super().launch_instance(argv=argv, **kwargs)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/traitlets/config/application.py", line 978, in launch_instance
    app.start()
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/nbconvertapp.py", line 426, in start
    self.convert_notebooks()
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/nbconvertapp.py", line 600, in convert_notebooks
    self.convert_single_notebook(notebook_filename)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/nbconvertapp.py", line 563, in convert_single_notebook
    output, resources = self.export_single_notebook(
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/nbconvertapp.py", line 491, in export_single_notebook
    output, resources = self.exporter.from_filename(
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/exporter.py", line 190, in from_filename
    return self.from_file(f, resources=resources, **kw)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/exporter.py", line 207, in from_file
    return self.from_notebook_node(
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/html.py", line 223, in from_notebook_node
    return super().from_notebook_node(nb, resources, **kw)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/templateexporter.py", line [38](https://github.com/tum-pbs/PhiFlow/actions/runs/3044041976/jobs/4904884808#step:7:39)6, in from_notebook_node
    nb_copy, resources = super().from_notebook_node(nb, resources, **kw)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/exporter.py", line 147, in from_notebook_node
    nb_copy, resources = self._preprocess(nb_copy, resources)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/exporter.py", line 3[44](https://github.com/tum-pbs/PhiFlow/actions/runs/3044041976/jobs/4904884808#step:7:45), in _preprocess
    self._validate_preprocessor(nbc, preprocessor)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbconvert/exporters/exporter.py", line 311, in _validate_preprocessor
    nbformat.validate(nbc)
  File "/opt/hostedtoolcache/Python/3.8.13/x64/lib/python3.8/site-packages/nbformat/validator.py", line [50](https://github.com/tum-pbs/PhiFlow/actions/runs/3044041976/jobs/4904884808#step:7:51)3, in validate
    raise error
nbformat.validator.NotebookValidationError: data.cells[{data__cells_x}] must be valid exactly by one definition (0 matches found)

Failed validating <unset> in notebook['data']['cells']:

On instance:
<unset>

[marscher]

After receiving the newly introduced warning about missing cell ids MissingIDFieldWarning, I transformed my notebooks to have the IDs generated and saved on disk.
But the validation now fails as reported by @holl-

I tried to follow it in the debugger, but there seems no schema is being used to validate the data at all...

Since this is a blocker of the new version, I'd kindly ask you guys to look into this quickly. Thanks a lot!

[marscher]

With nbformat-5.7 the validation message about ids has gone. But I had to regenerate the notebooks with the same version and omit the major/minor version (4, 5) in normalize().

[mspronesti]

This error seems to be persisting even in 5.7.0. Only reverting to 5.4.0 worked for me.