It's an old habit that probably goes back to the first versions of LyX on Windows (I used to work with LyX on Cygwin before). It seems to me that the bundle had been introduced so as not to have to worry about installing, at the good version, a whole lot of accessory software like the image converter, python, dictionaries etc., as well as a minimal version of LaTeX (which is however insufficient in some cases).
2018-03-03 18:17 GMT+01:00 Scott Kostyshak <skost...@lyx.org>: > On Sat, Mar 03, 2018 at 06:14:33AM +0000, Emile Lunardon wrote: > > I managed to have a successfull installation with the installer version > of > > LyX2.3, keeping the anti-virus «Windows Defender» active. So the problem > is > > well linked to the bundle and its interaction with Miktex 2.9. > > Good to know. Why were you using the bundle when you already have MiKTeX > installed? Was your expectation that LyX would overwrite your current > MiKTeX installation with the bundled one, or that they would be > installed side-by-side? > > Scott >