MarvinSketch in browser

Hi,

My chemistry classes frequently use MarvinSketch as part of the online homework.  On one specific assignment, the applet doesn't load, and an error message comes up that simply says "Error  chemaxon/license/LicenseHandler".  The options are "Okay" and "Stack Trace"; the second option gives:

java.lang.NoClassDefFoundError: chemaxon/license/LicenseHandler

at chemaxon.license.LicenseManager.setLicenseFile(Unknown Source)

at chemaxon.marvin.common.swing.MolPanel.molInit(Unknown Source)

at chemaxon.marvin.sketch.swing.SketchPanel.molInit(Unknown Source)

at chemaxon.marvin.common.swing.MolPanel.init(Unknown Source)

at chemaxon.marvin.common.swing.MolPanel.init(Unknown Source)

at chemaxon.marvin.applet.JMSketch.createGUI(Unknown Source)

at chemaxon.marvin.applet.AbstractMarvinApplet.init(Unknown Source)

at chemaxon.marvin.applet.JMSketchLaunch.showApplet(Unknown Source)

at chemaxon.marvin.applet.AppletLaunch$2.run(Unknown Source)

at java.awt.event.InvocationEvent.dispatch(Unknown Source)

at java.awt.EventQueue.dispatchEventImpl(Unknown Source)

at java.awt.EventQueue.access$000(Unknown Source)

at java.awt.EventQueue$1.run(Unknown Source)

at java.awt.EventQueue$1.run(Unknown Source)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)

at java.awt.EventQueue.dispatchEvent(Unknown Source)

at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)

at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

at java.awt.EventDispatchThread.run(Unknown Source)

There are several reasons whey LicenseManager is not find by Marvin.

1. Java cache issue: Purge the Java cache and restart the browser solves the issue.

2. The required jar that includes LicenseManager class is missing from the server where the applet is located. In this case, nobody can access this jar.

3. Do you get this message at startup "The application's digital signature has an error. Do you want to run the application?"?  This message appears by old Marvin versions because the digital signiture that was used anno for build this applet has been already expired. It is just a warning message, let "Run" the applet. After that you may get another warning:

Java has discovered application components that could indicate a security concern.

This warning appears because Java 1.6.0_19 or newer versions does not let (by default) opening applet that refers to external resources (that are not wrapped into signed jars). If you get this warning, choose "No". It is required to let applet to load these resources. In newer Marvin versions this issue is solved by rewriting the loading of these resources. You can read more about this issue in this forum topic:

https://www.chemaxon.com/forum/ftopic6100.html

Is any above case fit to your problem?

Purging the cache worked, thanks.  I'd tried it a number of times before and it didn't fix the issue; not sure why it worked this time and not all the previous times.

Much appreciated.