Hi Eric,
On Oct 8, 2013, at 11:49 AM, Eric Jonzeck <jonzeck(a)lieferando.de> wrote:
  Hey guys,
 i run into an exception on my newly installed xwiki after klicking the
 register-button:
 HTTP Status 500 -
  _____
 type Exception report
 message
 description The server encountered an internal error () that prevented it
 from fulfilling this request.
 exception
 javax.servlet.ServletException: Servlet execution threw an exception 
[snip]
  root cause
 java.lang.NoClassDefFoundError: Could not initialize class
 com.xpn.xwiki.web.RegisterAction 
This is the error. It means you're missing some JAR in the XWiki's WEB-INF/lib
directory.
Namely the xwiki-plartform-*oldcore*.jar
  note The full stack trace of the root cause is
available in the Apache
 Tomcat/6.0.35 logs.
 Do you have any idea why? I installed it via aptitude on my ubuntu 12.04
 x64. 
Not sure what went wrong. I've never installed XWiki this way myself. I'll let
those with more experience chime in.
Thanks
-Vincent