I got a similar problem with Jabref 4.3.1. I found out that openjfx was recenty upgraded in unstable to version 11 and does not work with java 8.
I went to snapshot.debian.org and downloaded the correct openjfx version for my openjdk and made jabref work again.
openjfx is a very odd package, as it does not depends on the version of openjdk in the package but it seems to only work for the exact java version. According to the debian issue tracker, there is no intention to create a separate openjfx-8 package… Odd enough, there is no openjfx 181 but only 171…
For me the combination of
openjdk version "1.8.0_171"
OpenJDK Runtime Environment (build 1.8.0_171-8u171-b11-2-b11)
OpenJDK 64-Bit Server VM (build 25.171-b11, mixed mode)
and
Package: openjfx
Version: 8u171-b11-2
worked.