bug#24866: AucTeX not working on Emacs 25.1.1 for Mac

[emacs user]

Hi, just to say that I am having the same/ related problem: emacs
25.1, latest auctex from elpa, on a Mac OS X Sierra.  auctex seems to
work fine, but preview latex is not recognized.  used to work
previously, although am not sure if this is due to the upgraded emacs
or auctex versions.  thanks for any hints...  E

________________________________
Hi,

Might be Emacs and not AucTeX that cause the problems but it was
AucTeX that triggered my problems, and I wanted to make you aware...

I have a clean installation of Emacs for Mac 25.1.1 and pulled a fresh
auctex from github (see script below).
In my .emacs I have reduced everything to to (load "auctex.el" nil t t)
When I try to open a LaTeX-file I get the  message:

File mode specification error: (void-variable LaTeX-preview-setup)

Any clues or instructions?

As a follow-up: I have downgraded to Emacs 24.5 and AucTeX pulled from
git works fine there.

Best,
Lars