To fix the JNLP file not opening problem, update or install Java Runtime Environment, set JRE as the default app, or install JRE 64-bit.

Since JNLP files are simply Java Web Start files that open applications through an Internet browser, any browser that works in Windows 8.1 will open a JNLP file as long as you have Java installed.

After installing the open web start in Mac os. I opened the JNLP application. By default, it is opening via the JAVA web start. For opening it VIA open web start launcher the user needs to click on ...

net.sourceforge.jnlp.LaunchException: Fatal: Launch Error: Could not launch JNLP file. The application has not been initialized, for more information execute javaws/browser from the command line and ...