Make sure to downgrade:
Make sure that you have an up to date Java 8 platform installed on your host system. Zulu is currently the recommended Java platform for openHAB. Download and installation instructions can be found on Azul Systems’ Zulu website. Oracle Java is also suitable for most configurations but licencing restrictions may apply. OpenJDK may also be used, but it has some known limitations with openHAB and is not recommended.