ValueError when loading .dotx Word template – lack of native template support

[furrepanther]

Attempting to instantiate a Word template (.dotx) using python-docx.Document() fails with a ValueError. The file opens normally in Microsoft Word and conforms to the standard OOXML template structure.

Steps to Reproduce

from docx import Document
doc = Document(".dotx")

Actual Behavior

ValueError: file '.dotx' is not a Word file,
content type is 'application/vnd.openxmlformats-officedocument.wordprocessingml.template.main+xml'

Expected Behavior
The library should be able to load .dotx templates just like .docx documents, allowing developers to:

Read and apply existing style definitions

Retain header/footer content, watermarks, and embedded assets

Save new .docx files that preserve template formatting

Environment

python-docx version: (run pip show python-docx to confirm)

Python version: 3.11+

Platform: Linux/Windows

Use Case
Corporate document generation workflows (e.g., Alignment Guard Labs) depend on .dotx templates for visual standards and branding. The current limitation forces manual template application in Word post-generation.

Proposed Enhancement
Add native .dotx support or a helper API such as Document.from_template(path) to copy all style and part relationships into a new .docx.

[coderamaster]

Hi! I've reproduced the issue. The error occurs because python-docx doesn't recognize the template content type. I'd like to work on adding .dotx template support. Let me investigate and submit a PR.

[EwoutH]

Ran into this myself. As a workaround until the PR lands: copy the .dotx to a temp .docx and patch [Content_Types].xml inside the zip to swap wordprocessingml.template.main+xml → wordprocessingml.document.main+xml. That's the only difference. Styles, headers, and numbering all carry over fine.

But it would be nice if python-docx got native support.

What's the status on #1537? And what's needed to move it forward?