I am not able launch JNLP applications using "Java Web Start"?

Java web start should be enabled.
Check if javaws (Java web start is enabled for your system), Use below command in console to open java control panel.

javaws -viewer

I know this is an older question but this past week I started to get a similar problem, so I leave here some notes regarding the solution that fits me.

This happened only in some Windows machines using even the last JRE to date (1.8.0_45).

The Java Web Start started to load but nothing happened and none of the previous solution attempts worked.

After some digging i've found this thread, which gives the same setup and a great explanation.

https://community.oracle.com/thread/3676876

So, in conclusion, it was a memory problem in x86 JRE and since our JNLP's max heap was defined as 1024MB, we changed to 780MB as suggested and it was fixed.

However, if you need more than 780MB, can always try launching in a x64 JRE version.

i had the same problem here. go to your Java Control Panel and Settings... Uncheck 'Keep temporary files on my computer'. Apply changes and try again your .jnlp

Note: Tested on different machines; Windows Server 2012, Windows Server 2008 and Windows 7 64bit. Java Version: 1.7++ since my jnlp app is built on 1.7

Please let me know your feedback too. :D

Have a look at what happens if you run javaws.exe directly from the command line.