> And So it is normal that it fails on so many files with the error
> "TeX-auto-parse-region: Wrong type argument: stringp, nil"?  This
> seems very weird to me...

Usually not, and I'm seeing this for the first time, but to be honest,
I'm not willing to debug it.

> yes, I used `M-x list-packages RET', searched for AUCTeX with C-s, and
> then entered the package and chose "install".  I am not sure whether I
> saw the "obsolete" description the first time I searched for the
> package or only the second time.

Is it still present?

Best, Arash