Java Web Start technology allows activating either "trace" or "log" system (or the two of them).
To activate them:
- launch the (same version used when launching JNLP file of) Java Web Start viewer:
- close the viewer main window
- go to the advanced panel and switch on either "trace" or "log", or the two of them
The next time you will use the same version of Java Web Start, it will produce log files.
It is particularly needed when the console vanishes after showing error stack(s) (usually when the launched application fails startup).
You can get and analyse log/trace, looking under your home directory: