I suppose one can work around by not creating any gallery for those Aliases at all,

{% if objname not in ['AliasOfFoo', 'OtherAlias', 'NextAlias'] %}

.. include:: {{module}}.{{objname}}.examples

.. raw:: html

    <div class="clearer"></div>

{% endif %}

but that is for sure not ideal, because (1) we loose the galleries, (2) we clutter the autosummary template with content specific stuff.

Sounds like a bug indeed and I am afraid I don't have any suggestions off the top of my head as how to solve or work around it. A PR fixing this would be welcome!

I am going to be frank: this is unlikely to be a priority until 0.14 is released.

If you had time to set-up a reproducible example outside of matplotlib, it would greatly help anyone to work on trying to fix this.

I created an example showing the issue. This can be found here: https://github.com/ImportanceOfBeingErnest/sphinx-mwe

There are two folders, one works just fine, the other contains a line creating an Alias class

MyClassAlias = MyClass

This will lead to the error being raised

D:\xyz\abc\dev\sphinx-mwe\sphinx-mwe-bug\doc\source\_as_gen\module.MyClassAlias.rst:12: 
WARNING: Problems with "include" directive path:
InputError: [Errno 2] No such file or directory: 'source/_as_gen/module.MyClassAlias.examples'.

I found out that when creating an example which actually uses the MyClassAlias class, this error does not occur. But of course we do not have examples for all those aliases around.