I am using a local web server on my computer to test a jar file that I am going to use the Java Network Launch Protocol (JNLP) to use that is going to be included in my website, but I am having a problem with Java not allowing the JNLP file to be run.

Application Blocked by Java Security

I tried to remedy the problem by adding localhost to my exception list in the Java Control Panel but the block message keeps coming up. How can I stop this?

Java Control Panel

  • "How can I stop this?" Click the link with 'more information'. Nov 4, 2014 at 23:49
  • 1
    @AndrewThompson You can safely assume that I looked at that link before posting here. Nov 5, 2014 at 0:10

1 Answer 1


(1) From what I read on the description of the exception site list it could be that you need to self sign your application. (But I would try the other suggestions first)

(2) What you also must ensure:

"For Java Web Start applications, the URL for the main JNLP file must be in the list. If the URL for the main JNLP file cannot be determined, then the exceptions do not apply to the RIA."

(3) Other than that I would play around with it a bit:

  • did you try adding some more entries to the list like or the actual IP?
  • do you use a specific port? If so you need to add it...
  • Did you chose the right protocol http vs https vs file?
  • The trick for me was adding the specific port number which is easy to overlook. http://localhost:6405/ This helped with SAP Business Objects.
    – Gabe
    Jan 9, 2017 at 22:49

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