1.2.1: sphinx warnings reference target not found

[kloczek]

On building my packages I'm using sphinx-build command with -n switch which shows warmings about missing references. These are not critical issues.

There are few other warnings as well. Here is the output with warnings:

+ /usr/bin/sphinx-build -n -T -b man doc build/sphinx/man
Running Sphinx v5.0.2
WARNING: Invalid configuration value found: 'language = None'. Update your configuration to a valid langauge code. Falling back to 'en' (English).
making output directory... done
WARNING: while setting up extension conf.py: The app.add_stylesheet() is deprecated. Please use app.add_css_file() instead.
loading intersphinx inventory from https://docs.python.org/3.5/objects.inv...
building [mo]: targets for 0 po files that are out of date
building [man]: all manpages
updating environment: [new config] 11 added, 0 changed, 0 removed
reading sources... [100%] plantweb/plantweb.render
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
writing... python-plantweb.3 { examples developer plantweb/plantweb plantweb/plantweb.__main__ plantweb/plantweb.args plantweb/plantweb.defaults plantweb/plantweb.directive plantweb/plantweb.main plantweb/plantweb.plantuml plantweb/plantweb.render } /home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/lib/plantweb/directive.py:docstring of plantweb.directive.defaults_provider:6: WARNING: py:data reference target not found: DEFAULT_CONFIG
docstring of plantweb.directive.Plantweb.required_arguments:2: WARNING: py:class reference target not found: docutils.parsers.rst.directives.images.Image
docstring of plantweb.directive.Plantweb.required_arguments:2: WARNING: py:class reference target not found: docutils.parsers.rst.Directive
/home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/doc/plantweb/plantweb.directive.rst:61: WARNING: py:class reference target not found: docutils.parsers.rst.directives.images.Image
/home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/doc/plantweb/plantweb.directive.rst:61: WARNING: py:class reference target not found: docutils.parsers.rst.Directive
/home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/doc/plantweb/plantweb.directive.rst:68: WARNING: py:class reference target not found: docutils.parsers.rst.directives.images.Image
/home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/doc/plantweb/plantweb.directive.rst:68: WARNING: py:class reference target not found: docutils.parsers.rst.Directive
/home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/doc/plantweb/plantweb.directive.rst:75: WARNING: py:class reference target not found: docutils.parsers.rst.directives.images.Image
/home/tkloczko/rpmbuild/BUILD/plantweb-1.2.1/doc/plantweb/plantweb.directive.rst:75: WARNING: py:class reference target not found: docutils.parsers.rst.Directive
done
build succeeded, 11 warnings.

You can peak on fixes that kind of issues in other projects
latchset/jwcrypto#289
click-contrib/sphinx-click@abc31069
latchset/jwcrypto#289
RDFLib/rdflib-sqlalchemy#95
sissaschool/elementpath@bf869d9e
jaraco/cssutils#21
pywbem/pywbem#2895