Medline search on Jabref 4.0 is not working anymore

I am using JabRef 4.0, Windows 7 6.1 amd64, Java 1.8.0_151. Medline search in JabRef was working so far but suddenly stopped working yesterday. Search is starting but never completes no matter what I am looking for. Suggestions?

Medline slightly changed their API recently, which throw JabRef off guard. @joerg.lenhard already implemented a fix and the development version should work again.