FULL PRODUCT VERSION :
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Client VM (build 14.2-b01, mixed mode, sharing)

java version "1.4.2_19"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_19-b04)
Java HotSpot(TM) Client VM (build 1.4.2_19-b04, mixed mode)


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


A DESCRIPTION OF THE PROBLEM :
Java Web Start that comes with JRE 1.6.0_15 and 16 fails to launch signed applications using JRE 1.4.2.  Previous versions of 1.6.0 work fine.

JRE 1.4 is required in the jnlp:
<j2se version="1.4" initial-heap-size="128m" max-heap-size="512m"/>

This error message is displayed in the JWS console:
#### Java Web Start Error:
#### java.lang.NoClassDefFoundError: java/security/CodeSigner

The error only occurs if there is more than one jar specified in the resources element of the jnlp file. It doesn't matter whether jnlp-servlet is used or not.

Short discussion of the issue can be found here:
http://forums.sun.com/thread.jspa?threadID=5402886



ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NoClassDefFoundError: java/security/CodeSigner
	at com.sun.javaws.security.SigningInfo.setContains(Unknown Source)
	at com.sun.javaws.security.SigningInfo.overlapChainLists(Unknown Source)
	at com.sun.javaws.LaunchDownload.checkSignedResourcesHelper(Unknown Source)
	at com.sun.javaws.LaunchDownload.checkSignedResources(Unknown Source)
	at com.sun.javaws.Launcher.prepareLaunchFile(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)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
<?xml version="1.0" encoding="ISO-8859-1"?>
<jnlp spec="1.0" codebase="$$codebase">
	<information>
		<title>Hello World!</title>
		<vendor>TIKE</vendor>
		<homepage href=""/>
		<description>Hello World!</description>
		<description kind="short">Hello World!</description>
	</information>
	<security>
		<all-permissions/>
	</security>
	<resources>
		<j2se version="1.4" initial-heap-size="128m" max-heap-size="512m"/>
		<jar href="HelloWorld.jar"/>
		<jar href="HelloWorld_resources.jar"/>
	</resources>
	<application-desc main-class="HelloWorld"/>
</jnlp>
   
---------- END SOURCE ----------

Release Regression From : 6u14
The above release value was the last known release where this 
bug was not reproducible. Since then there has been a regression.