@cyberian said in The Java JAR file “ubnt-discovery-v2.5.1.jar” could not be launched.:

Check the Console for possible error messages.

As mentioned on Oracle’s website, “The JRE will not show up in the Java Preferences list unless you install the full JDK.”

Q: I have Oracle’s version the JRE installed, but it is not listed in Java Preferences.

A: This is correct. The JRE will not show up in the Java Preferences list unless you install the full JDK.”

https://docs.oracle.com/javase/7/docs/technotes/guides/jweb/mac-faq.html