When trying to upgrade the collector to the latest version (19.209-5) it failed with the following java related errors.
INFO | jvm 1 | 2017/09/21 09:55:00 | WrapperSimpleApp Error: Class com.sumologic.scala.collector.Collector found but could not be initialized: java.lang.UnsupportedClassVersionError: com/sumologic/scala/collector/Collector : Unsupported major.minor version 52.0
ERROR | wrapper | 2017/09/21 09:55:02 | JVM exited while loading the application.
Log File: Collector.out.log
With the release of Collector version 19.209-5, the Sumo collector is built to target the Java 8 runtime and Java 6 and Java 7 are no longer supported as the collector runtime. If you are currently running the Collector with your own supplied JRE you will need to upgrade that JRE to version 8 or install JRE 8 within a secondary path, which can be used by the Collector. Please check Release Notes for version (19.209-5):
If the collector uses a binary package which is the tarball version - then the solution is to install the Java 8 JDK on the server. Once you have installed the JRE you will need to update the following file and property to point your Collector to the path for this version of the JRE.
After updating the JRE please re-run the upgrade and confirm the upgrade is successful.