FULL PRODUCT VERSION :
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) Client VM (build 20.1-b02, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
Web Start cache is empty.
Web Start cache is disabled.

A DESCRIPTION OF THE PROBLEM :
Cannot launch a Web Start application if the cache is disabled if the JNLP file uses extension elements. The cache is currently empty, the application is signed, and granted all permissions.

If the cache is enabled, Web Start works correctly. If the files were previously cached, Web Start also seems to work correctly.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a JNLP application that uses an extension.
2. Sign the JNLP application JARs.
3. Clear the Web Start cache.
4. Disable the Web Start cache.
5. Try to launch the JNLP application.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Web Start should launch the application.
ACTUAL -
Web Start will download the JARs, then fail to launch the application because it can't verify the JARs in the extension.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
EXCEPTION:

com.sun.deploy.net.JARSigningException: Found unsigned entry in resource: http://expunged:8080/content/jars/axis.jar
at com.sun.javaws.security.SigningInfo.getCommonCodeSignersForJar(Unknown Source)
at com.sun.javaws.security.SigningInfo.check(Unknown Source)
at com.sun.javaws.LaunchDownload.checkSignedResourcesHelper(Unknown Source)
at com.sun.javaws.LaunchDownload.checkSignedResources(Unknown Source)
at com.sun.javaws.Launcher.prepareResources(Unknown Source)
at com.sun.javaws.Launcher.prepareAllResources(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_26
Using JRE version 1.6.0_26-b03 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\expunged
----------------------------------------------------
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:
#### Found unsigned entry in resource: http://expunged:8080/content/jars/axis.jar

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
* Turning on the cache works around this issue on the client end.
* Not using extension elements works around this issue on the server end.