Wrong content type of a dotx template

[Lennonka]

Sphinx output:

Exception occurred:
  File "/usr/local/lib/python3.8/dist-packages/docx/api.py", line 28, in Document
    raise ValueError(tmpl % (docx, document_part.content_type))
ValueError: file 'source/internal-long-style.dotx' is not a Word file,
content type is 'application/vnd.openxmlformats-officedocument.wordprocessingml.template.main+xml'

What is the correct content type? My dotx file is a direct export from MS Word. Are there any limitations to versions of MS Word? Or to cloud/desktop variants of MS Office?

Error log:

# Sphinx version: 3.5.1
# Python version: 3.8.5 (CPython)
# Docutils version: 0.15 release
# Jinja2 version: 2.11.3
# Last messages:
#   reading sources... [ 66%] 01 Decision Record
#   reading sources... [100%] index
#   
#   looking for now-outdated files...
#   none found
#   pickling environment...
#   done
#   checking consistency...
#   done
#   preparing documents...
# Loaded extensions:
#   sphinx.ext.mathjax (3.5.1) from /usr/local/lib/python3.8/dist-packages/sphinx/ext/mathjax.py
#   sphinxcontrib.applehelp (1.0.2) from /usr/local/lib/python3.8/dist-packages/sphinxcontrib/applehelp/>
#   sphinxcontrib.devhelp (1.0.2) from /usr/local/lib/python3.8/dist-packages/sphinxcontrib/devhelp/__in>
#   sphinxcontrib.htmlhelp (1.0.3) from /usr/local/lib/python3.8/dist-packages/sphinxcontrib/htmlhelp/__>
#   sphinxcontrib.serializinghtml (1.1.4) from /usr/local/lib/python3.8/dist-packages/sphinxcontrib/seri>
#   sphinxcontrib.qthelp (1.0.3) from /usr/local/lib/python3.8/dist-packages/sphinxcontrib/qthelp/__init>
#   alabaster (0.7.12) from /usr/local/lib/python3.8/dist-packages/alabaster/__init__.py
#   sphinx.ext.todo (3.5.1) from /usr/local/lib/python3.8/dist-packages/sphinx/ext/todo.py
#   docxsphinx (unknown version) from /usr/local/lib/python3.8/dist-packages/docxsphinx/__init__.py
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/sphinx/cmd/build.py", line 280, in build_main
    app.build(args.force_all, filenames)
  File "/usr/local/lib/python3.8/dist-packages/sphinx/application.py", line 352, in build
    self.builder.build_update()
  File "/usr/local/lib/python3.8/dist-packages/sphinx/builders/__init__.py", line 293, in build_update
    self.build(['__all__'], to_build)
  File "/usr/local/lib/python3.8/dist-packages/sphinx/builders/__init__.py", line 360, in build
    self.write(docnames, list(updated_docnames), method)
  File "/usr/local/lib/python3.8/dist-packages/docxsphinx/builder.py", line 77, in write
    self.prepare_writing(docnames)
  File "/usr/local/lib/python3.8/dist-packages/docxsphinx/builder.py", line 62, in prepare_writing
    self.writer = DocxWriter(self)
  File "/usr/local/lib/python3.8/dist-packages/docxsphinx/writer.py", line 83, in __init__
    dc = Document(os.path.join('source', self.template_dir))
  File "/usr/local/lib/python3.8/dist-packages/docx/api.py", line 28, in Document
    raise ValueError(tmpl % (docx, document_part.content_type))
ValueError: file 'source/internal-long-style.dotx' is not a Word file,
content type is 'application/vnd.openxmlformats-officedocument.wordprocessingml.template.main+xml'

[hugobuddel]

The 'template' is actually an empty word document, a docx, so not a true template. We should document this better (see also #39 ) and perhaps indeed use a proper dotx template file.

[Lennonka]

Thanks for the info!
By the way, I can help with the docs (as a volunteer), I'll be available in June as I have too many projects on my plate right now :)