Using JWS 1.0.1 to run demos on http://java.sun.com/products/javawebstart:

It fails with error Message :

An error occurred while launching/running the application.

Title: SwingSet2
Vendor: Sun Microsystems, Inc.
Category: Download Error

Missing version field in response from server when accessing resource:
(http://dlres.java.sun.com/servlet/com.sun.jsc.javasoft.jaws.JNLPServlet/j2s
e/j2re-native-win.jar, 1.3.0_02)"

This is happening because javaws.cfg file has only one entry as shown below :

javaws.cfg.jre.0.platform=1.4.0
javaws.cfg.jre.0.product=1.4.0-beta
javaws.cfg.jre.0.path=C:\\Program Files\\JavaSoft\\JRE\\1.4\\bin\\javaw.exe
javaws.cfg.jre.default=0

JWS when encountered the "beta" word is making an attempt to download the 1.3.0_02 version of JRE and is failing with the above error message during the autodownload process.

If I remove the word beta and modified it to

javaws.cfg.jre.0.product=1.4.0

It works fine because then Java Web Start considers the 1.4 to be a valid JRE to run the demos, and does not attempt an auto-download.

Please note that this issue was reported by one of the External developers using the javawebstart feedback alias.