I cant say I know a lot about JNLP files.. other then that they’re typically opened by “Java Web Start” an application hiding within the Java program folder under the guise of “javaws” …and that in itself is a tidbit of information I didnt know until I had the joy of troubleshooting a JNLP that java wouldnt open.
The Problem: you have a web application that wont execute.. the jnlp downloads but once its executed, windows doesn’t know what program to use.
the Details: windows prompts for a program to open the JNLP but there is none… even in the java folder there is nothing that opens it.. redownloading the latest java release doesnt change this..
The Solution: after much troubleshooting, and frustration, the only fix was to downgrade java.
Resources: Java’s website explaining Java web start.