Steps to reproduce:
- Setup the XEM 4.5.3 WAR with Jetty/Hsqldb
- Install the UI with the DW or by importing the corresponding XAR
- Stop the server and replace the xwiki folder from webapps with the one from the 5.4.1 war
- Start the server
You'll see the Main.WebHome page without any redirect to DW. Reproduces also on Tomcat/Mysql. Doesn't reproduce when upgrading from 4.5.3 to 5.2.4.