The main change in this release from previous versions of Wowza Streaming Engine is the replacement of Oracle Java SE JRE 9.0.4 with OpenJDK Java SE JRE 11.0.2.
When deploying Wowza to a new server, a standalone Java installation is not required. All required JRE 11.0.2 components are included in the release installer.
The procedure for updating an already installed Wowza Streaming Engine version below 4.8.18 is somewhat more complicated. Before running the update script, you need to stop the Wowza services (there are two of them) and separately install JRE 11.0.2. The easiest way to do this is to download the JRE 11.0.2 distribution from your wowza.com profile. From the contents of the downloaded archive, depending on the platform, you need to extract the corresponding directory with Java components. Copy the directory to the directory with Wowza installed under the name JRE11 for example and change the java symlink to this new directory (for the Windows platform, change JAVA_HOME environment variable). After that, you can run the Wowza version update script itself directly.