Why does displacy raise a warning when rendering Docs parsed using a Stanza language model via spacy-stanza?

[thiippal]

Hey!

I used spacy-stanza to load a Stanza language model for Finnish into spaCy.

I then applied the model to some texts to get a Doc object. I then used the sents attribute to extract Span objects for sentences, which I stored into a list named sents_fi.

I then wanted to visualise the syntactic dependencies for the first Span in the list.

# Import the displacy submodule
from spacy import displacy

# Use the render function to render the first item [0] in the list 'sents_fi'.
# Pass the argument 'style' with the value 'dep' to visualise syntactic dependencies.
displacy.render(sents_fi[0], style='dep')

This works just fine, but raises the following warning:

[W109] Unable to save user hooks while serializing the doc. Re-add any required user hooks to the doc after processing.

Any idea what causes this warning?

[adrianeboyd]

This is a relatively cryptic error that you can safely ignore or filter if you're just using displacy. I think we should consider filtering it out ourselves with displacy, since it's really confusing.

What's going on underneath in case you're interested: spacy-stanza add user hooks for token vectors if the stanza model includes pretrained word embeddings. As an internal processing step, displacy serializes the doc with doc.to_bytes, which is what leads to this warning, since it can't serialize the user hooks.

[adrianeboyd]

Should be fixed by #7419.