I'm new to LyX, and using LyX 2.0 for Windows. When I select a template from "File"->"New from template" it shows a alert with title

"document class not available"

containing the text like

selected document class


require an unavailable external file and asks for


Where can I get the scrbook.cls and how to install it?

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    – Werner
    Jan 2, 2012 at 2:25
  • 6
    Are you sure you have a TeX distribution installed? LyX itself requires either MiKTeX or TeXLive to be installed as well as LyX itself. (The installer should have installed MikTeX, I think.)
    – Alan Munn
    Jan 2, 2012 at 2:33

3 Answers 3


Besides TeX/LaTeX, you need to install the KOMA-Script bundle, scrbook belongs to it, as all classes and packages with a name starting with scr.

  • If you use MiKTeX, start the MiKTeX package manager (mpm) and install the package koma-script, the link points to the package description on the MiKTeX homepage.

  • If you use TeX Live, start the TeX Live Manager (tlmgr) and install the package koma-script. It can also be done on the command prompt: tlmgr install koma-script.

  • 1
    Aren't these both standardly part of both TeX Live and MikTeX?
    – Alan Munn
    Jan 2, 2012 at 16:21
  • 1
    @AlanMunn KOMA-Script is not part of basic MiKTeX, also TeX Live offers different installation schemes.
    – Stefan Kottwitz
    Jan 2, 2012 at 16:25

LyX requires a TeX distribution to operate. A TeX distribution is the collection of programs, fonts and packages/classes that are required to produce documents with TeX. For Windows, the LyX installer should have installed MikTeX if it found no distribution installed. If that didn't happen then you may need to install MikTeX separately. You can get MikTeX here: http://miktex.org/.

You can verify whether you have a working distribution by typing in latex in the START menu. You should see something like the following: (this screenshot is from a German system, but other than that, the display should be similar).


(If you type MiKTeX you should also see something related MikTeX itself).

Alternatively you can opening in a command window (windows key+R CMD) and typing:

latex -v

If these methods fail to turn up anything, then you need to install MikTeX yourself.


Try the following:

  • Open Lyx
  • Click on Tools Menu/Reconfigure
  • Lyx will be unresponsive until reconfigure completes
  • restart Lyx

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