I am seeing this error while building older docs.
$ make htmlview
sphinx-build -b djangohtml -n -d _build/doctrees -D language=en . _build/html
Running Sphinx v3.0.3
loading translations [en]... done
loading intersphinx inventory from https://docs.python.org/3/objects.inv...
loading intersphinx inventory from http://sphinx-doc.org/objects.inv...
loading intersphinx inventory from https://pythonhosted.org/six/objects.inv...
loading intersphinx inventory from https://django-formtools.readthedocs.io/en/latest/objects.inv...
loading intersphinx inventory from http://initd.org/psycopg/docs/objects.inv...
WARNING: failed to reach any of the inventories with the following issues:
intersphinx inventory 'https://pythonhosted.org/six/objects.inv' not fetchable due to <class 'requests.exceptions.HTTPError'>: 404 Client Error: Not Found for url: https://pythonhosted.org/six/objects.inv
intersphinx inventory has moved: http://initd.org/psycopg/docs/objects.inv -> https://www.psycopg.org/docs/objects.inv
intersphinx inventory has moved: http://sphinx-doc.org/objects.inv -> https://www.sphinx-doc.org/en/master/
WARNING: failed to reach any of the inventories with the following issues:
intersphinx inventory 'http://sphinx-doc.org/objects.inv' not readable due to ValueError: unknown or unsupported inventory version: ValueError('invalid inventory header: ')
building [mo]: targets for 0 po files that are out of date
building [djangohtml]: targets for 415 source files that are out of date
updating environment: [new config] 415 added, 0 changed, 0 removed
reading sources... [ 2%] howto/auth-remote-user
Exception occurred:
File "/home/umair/Develop/django/docs/_ext/djangodocs.py", line 230, in run
env.note_versionchange(node['type'], node['version'], node, self.lineno)
AttributeError: 'BuildEnvironment' object has no attribute 'note_versionchange'
The full traceback has been saved in /tmp/sphinx-err-mpwd5k7b.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
Makefile:53: recipe for target 'html' failed
make: *** [html] Error 2