You might see the error message Error: Could not find or load main class org.jabref.JabRefMain. This means, you do not have JavaFX support activated in your Java runtime environment. This typically happens if you use OpenJDK, where one needs to setup OpenJFX separately.
I am on Debian/Ubuntu and clicking on the JabRef icon works, but I cannot start JabRef from the command line. What is wrong?
You have several Java Virtual Machines installed, and under the command line the wrong one is chosen. Have a look at the previous question that tells you how to change the virtual machine used.
Does JabRef run under free Java (Classpath, Kaffee, GCJ, etc.)?
As far as we know, JabRef is not yet running on these free JVMs, due of our dependencies. However, JabRef is reported to run nicely on the IcedTea runtime, which is based on the OpenJDK built with GNU Classpath to fill in missing classes. Some issues have been encountered with the look and feel (see issues #393 and #2003). Please let us know if newer versions give different results. If you have an idea or the expertise to make JabRef work under Classpath, let us know.
Everything looks too big or too small. How can I change it to to a more reasonable size?
In the background, JabRef uses JavaFX. Applications using JavaFX can be scaled via java -Dglass.gtk.uiScale=1.5 -jar <application>.jar. If you have installed JabRef via a package manager, you probably don't have a .jar file but a binary file. In this case, you need to find your JabRef.cfg in your installation folder (possibly located at /opt/JabRef/lib/app/JabRef.cfg) and add in the section [JavaOptions] the line -Dglass.gtk.uiScale=1.5. Then, restart JabRef. Try finding a value that is suitable for you. On high resolution displays, values around 1.5 seem to be reasonable.
