Linux
Is there any way to include JabRef in the start menu of Ubuntu?
Yes, there is. See http://askubuntu.com/a/721387/196423 for details.
JabRef does not start under Linux! What can I do?
JabRef 5.x
JabRef comes with a bundled JRE. There is no need to install Java separately. Thus, there should be no issues at start up.
JabRef 4.x
JabRef requires Java 8
Please follow the steps provided on our installation page. JabRef 4.x does not run under Java 9 or newer. See https://github.com/JabRef/jabref/issues/2594
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.
For Ubuntu you may also have a look at the Ubuntu page on Java.
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.
Where can I find JabRef's log files?
A: On Linux, the path to the log files is ~/.local/share/jabref/logs/$version/