Problem:

After installing fresh Release 12 instance (12.1.3), attempted to log on to application from client PC (Windows XPSP3). Was able to log on to R12, but forms could not be launched. The following message was displayed on the Java console:

load: class oracle/apps/fnd/formsClient/FormsLauncher.class not found.
java.lang.ClassNotFoundException: oracle.apps.fnd.formsClient.FormsLauncher.class
	at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
	at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
	at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
	at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Exception: java.lang.ClassNotFoundException: oracle.apps.fnd.formsClient.FormsLauncher.class

However, other client machines (Windows 7) were able to log on and launch the forms.

Solution:

After enabling logging (Control Panel > Java > Advanced tab > Debugging, check all options), the ‘java.net.SocketException: Connection reset’ error was seen in the Java console. This indicated a network issue rather than a Java or browser issue. The EBS server (192.168.63.49) was on a different network from the client PCs (200.65.1.x). Therefore, a network route was added to keep the connection alive:

route add 192.168.63.0 mask 255.255.255.0 200.65.1.1 -p