@lskerritt It looks like you are using a Java 14 runtime during the build that is failing. Currently Java 14 is not support though. See also Issue java 14: java.lang.NoClassDefFoundError: java/util/jar/Pack200 and https://jira.sonarsource.com/browse/SONARJAVA-3270.
Can you provide some more specifics on your build especially when it relates to Java. What is your source version, your targeted compile version?