The MetadataControlListener class was introduced in Lightstreamer Server version 7.1.0 (as part of the java in-process SDK version 7.2.0).
However, since Lightstreamer Server version 7.1.2, the jar that contains this class has changed place.
Up to 7.1.1 it was Lightstreamer/lib/ls-adapter-interface.jar
From 7.1.2, that library (now part of the java in-process SDK version 7.3.0, which has become open-source) is now included as Lightstreamer/lib/adapters/ls-adapter-inprocess-7.3.0.jar
The launch scripts in Lightstreamer/bin/unix-like have changed to add it to the classpath.
Perhaps you expected fewer changes in this upgrade and are still using the previous launch script?