This is the next release of Apache Hadoop 2.9 line. It contains 204 bug fixes, improvements and enhancements since 2.9.1.
Users are encouraged to read the overview of major changes since 2.9.1. For details of 204 bug fixes, improvements, and other enhancements since the previous 2.9.1 release, please check release notes and changelog detail the changes since 2.9.1.