External Launch Error: Could not determine location of javaws.jar on Linux Mint

[NCothran]

After a recent Linux update, whenever I try to run a .JNLP file with Openwebstart I am getting this error:

net.sourceforge.jnlp.LaunchException: Fatal: External Launch Error: Could not determine location of javaws.jar. An attempt was made to launch a JNLP file in another JVM, but the javaws.jar could not be located. In order to launch in an external JVM, the runtime must be able to locate the javaws.jar file.
at net.sourceforge.jnlp.Launcher.launchExternal(Launcher.java:289)
at net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:368)
at net.sourceforge.jnlp.Launcher.access$300(Launcher.java:72)
at net.sourceforge.jnlp.Launcher$TgThread.run(Launcher.java:661)
Caused by: java.lang.NullPointerException
at com.openwebstart.jvm.LocalRuntimeManager.loadRuntimes(LocalRuntimeManager.java:148)
at com.openwebstart.jvm.JavaRuntimeManager.getJavaRuntimeProvider(JavaRuntimeManager.java:29)
at com.openwebstart.extensionpoint.OwsExtensionPoint.createJvmLauncher(OwsExtensionPoint.java:36)
at net.sourceforge.jnlp.Launcher.launchExternal(Launcher.java:286)

On top of that, when I try to open Openwebstart settings it hangs on the initial banner and never opens, so I can't change any of the settings.

Any ideas?

[NCothran]

On further examination, this appears to be a permissions issue. If I run the JNLP files as sudo from the terminal it opens, but simply clicking them and running them gives the error. How can I fix that?