I’m trying to use the SWI-Prolog JPL library, but I’m having problems. I’m trying

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Editorial Team

Asked: May 31, 20262026-05-31T22:59:23+00:00 2026-05-31T22:59:23+00:00

I’m trying to use the SWI-Prolog JPL library, but I’m having problems.

I’m trying to let my Eclipse project access JPL, but when I try to start the program, I get the following error:

Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkError: no jpl in java.library.path

I copied the jpl.jar into my project directory, and I set it on the build path. Additionally, I pass the following VM arguments:

-Djava.library.path="C:\Program Files\Prolog\bin"

(That’s the directory where Prolog was installed).

What am I doing wrong?

EDIT: I don’t seem to have the libpl.dll anywhere on my computer. Could this be causing my problem?

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Editorial Team · Answer 1 · 2026-05-31T22:59:24+00:00

Editorial Team

The jvm.dll of your running JDK/JRE must be available in your system PATH so that jpl.dll from java.library.path loads properly.

You have to take care to 32 bits / 64 bits consistency between your JPL installation and your running JVM – so do not try any mix.

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