Not sure if it is a blocker, or if I was impatient.
This is exactly what I did :
1/ logged in http://server:9000
2/ was redirected to http://server:9000/setup
3/ Had JS error, clicked on the setup button
4/ Stayed idle for a long time (about 10 minutes)
5/ I then type http://server:9000 in the browser
6/ was offered to upgrade db from version 20 to 38
7/ Clicked setup, had the JS error
8/ install crashed
By the way, the JS error is not there in Firefox 3, only IE