Since the docsbuild-scripts [1] upgraded its sphinx-build [2], we're having this error when building the docs:

    ! Undefined control sequence.
    \py@authoraddress -> \strong

    {Python Software Foundation}\\ Email: \email {d...
    l.58 \sphinxtableofcontents
                           
    !  ==> Fatal error occurred, no output PDF file produced!


it looks like to be from conf.py line 97 [3]:

conf.py-95-# Additional stuff for the LaTeX preamble.
conf.py-96-latex_elements['preamble'] = r'''
conf.py:97:\authoraddress{
conf.py-98-  \strong{Python Software Foundation}\\
conf.py-99-  Email: \email{docs@python.org}
conf.py-100-}


 [1]: https://github.com/python/docsbuild-scripts 
 [2]: we merged https://github.com/python/docsbuild-scripts/pull/12
 [3]: https://github.com/python/cpython/blob/909a6f626ff343937cd3f06fda996870e7890724/Doc/conf.py#L97

New changeset da9b4cfb488119f2493a762fcb1d85c58494f51d by Zachary Ware (François Magimel) in branch 'master':
bpo-31423: Fix building the PDF documentation (GH-3693)
https://github.com/python/cpython/commit/da9b4cfb488119f2493a762fcb1d85c58494f51d

New changeset 6de35849cb7a18bfaad828eb57a2e6caa7978690 by Zachary Ware in branch '3.6':
[3.6] bpo-31423: Fix building the PDF documentation (GH-3693) (GH-3699)
https://github.com/python/cpython/commit/6de35849cb7a18bfaad828eb57a2e6caa7978690

New changeset da86874a3d8f882d6aedd882b2e27f59b59d6798 by Zachary Ware in branch '2.7':
[2.7] bpo-31423: Fix building the PDF documentation (GH-3693) (GH-3700)
https://github.com/python/cpython/commit/da86874a3d8f882d6aedd882b2e27f59b59d6798

Pending results of actual builds on docs.p.o, this should be fixed.

Thanks for looking into this.  See also https://github.com/python/psf-salt/issues/118 where the question arose whether the version of Tex Live on docs is new enough.  I'm no expert at anything Tex but the odd thing is that I had been able to build dist docs on my current Debian (testing) system without this change.  Let's see what happens on docs after the daily full doc build.

Good news! It appears that the changes supplied by @linkid have indeed fixed the daily downloadable doc build failures, 3.7, 3.6, and 2.7 docs were built successfully and the 404s are gone.  Thanks everyone for helping with this!

Seems like people are seeing 404s when downloading docs today. By any chance this issue is related?

> Seems like people are seeing 404s when downloading docs today.

Do you have specific URLs or web pages?  Or a link to where this was discussed?  I just did a quick look at some of the download pages and everything worked for me.

Sorry!! Yesterday morning I received 50+ emails all about document download page is 404. Reading those again, turns out these are older emails from a week before, somehow just showing up in my mailbox.
I think everything is good here. :)

Thanks!

New changeset a74ce09c738c3e3aa89994bf31049cb914dca389 by Ned Deily (Zachary Ware) in branch '3.6':
[3.6] bpo-31423: Fix building the PDF documentation (GH-3693) (GH-3699)
https://github.com/python/cpython/commit/a74ce09c738c3e3aa89994bf31049cb914dca389