FULL PRODUCT VERSION :
java version "1.6.0_14"
Java(TM) SE Runtime Environment (build 1.6.0_14-b08)
Java HotSpot(TM) Client VM (build 14.0-b16, mixed mode, sharing)


ADDITIONAL OS VERSION INFORMATION :
Windows XP  SP2

EXTRA RELEVANT SYSTEM CONFIGURATION :
The server is on our client's network which we access via a "Juniper Network Connect" vpn solution (v6.4.0.14343)

A DESCRIPTION OF THE PROBLEM :
In verifying our application against JRE 1.6.0_14 we have encountered an issue which is not present in the previous JRE (1.6.0_13).  The application is normally launched by a JNLP link on a server webpage, however this now throws the following error:-

java.io.IOException: Unable to tunnel through proxy.  Proxy returns "HTTP/1.1 403 Forbidden"

This error was originally thrown during a Spring RMI call from the application after launch, but having cleared the webstart application cache, it is now thrown when trying to load the jnlp resource.

The only way to workaround this is to remove the JRE, and revert back to 1.6.0_13 or earlier.  I've tested versions 15 and 16 as well and they exhibit the same problem.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Start an application over a VPN connection, using 1.6.0_14 as the client side JRE.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The application should start as normal
ACTUAL -
The webstart console throws the "Unable to tunnel through proxy" error.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Taken from the webstart console.

Exception

com.sun.deploy.net.FailedDownloadException: Unable to load resource: https://<server>:<port>/<path>/Applicationlauncher.jnlp
	at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
	at com.sun.javaws.Launcher.updateFinalLaunchDesc(Unknown Source)
	at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
	at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
	at com.sun.javaws.Launcher.launch(Unknown Source)
	at com.sun.javaws.Main.launchApp(Unknown Source)
	at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
	at com.sun.javaws.Main$1.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

Wrapped Exception

java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 403 Forbidden"
	at sun.net.www.protocol.http.HttpURLConnection.doTunneling(Unknown Source)
	at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(Unknown Source)
	at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
	at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
	at com.sun.deploy.net.BasicHttpRequest.doGetRequest(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
	at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
	at com.sun.javaws.Launcher.updateFinalLaunchDesc(Unknown Source)
	at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
	at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
	at com.sun.javaws.Launcher.launch(Unknown Source)
	at com.sun.javaws.Main.launchApp(Unknown Source)
	at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
	at com.sun.javaws.Main$1.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

Console

Java Web Start 1.6.0_14
Using JRE version 1.6.0_14-b08 Java HotSpot(TM) Client VM
User home directory = D:\Documents and Settings\bz605r
----------------------------------------------------
c:   clear console window
f:   finalize objects on finalization queue
g:   garbage collect
h:   display this help message
m:   print memory usage
o:   trigger logging
p:   reload proxy configuration
q:   hide console
r:   reload policy configuration
s:   dump system and deployment properties
t:   dump thread list
v:   dump thread stack
0-5: set trace level to <n>
----------------------------------------------------
#### Java Web Start Error:
#### Unable to load resource: https://<server>:<port>/<path>/ApplicationLauncher.jnlp



REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
The only workaround is to use JRE1.6..0_13 on the client side.

Release Regression From : 6u13
The above release value was the last known release where this 
bug was not reproducible. Since then there has been a regression.