The Apache Flink Community is pleased to announce the fourth bug fix release of the Flink 1.20 series.
This release includes 41 bug fixes, vulnerability fixes, and minor improvements for Flink 1.20. Below you will find a list of all bug fixes and improvements (excluding improvements to the build infrastructure and build stability). For a complete list of all changes see: JIRA.
We highly recommend all users upgrade to Flink 1.

Flink is an open-source stream processing framework for building real-time data applications, offering powerful features for data processing, analytics, and event-driven architectures. Developers can learn about stream processing concepts, event-driven architectures, and real-time analytics techniques to build scalable and fault-tolerant data pipelines for processing large volumes of data in real-time.

Flink

Apache Flink 1.20.4 has been released as the fourth bug fix update in the 1.20 series. It includes 41 bug fixes, vulnerability fixes, and minor improvements. Notable fixes address RocksDB state TTL class loader issues, SQL hint dropping when combining SELECT statements, wrong results from STDDEV/VAR functions with FILTER conditions, unaligned checkpoint recovery failures, PyFlink thread mode issues, sensitive data exposure in debug logs, and Flink WebUI breakage in Chrome 144+. Improvements include updated cipher suite defaults, dependency upgrades (lz4-java to 1.10.3, pemja to 0.5.6), and documentation redirect enhancements. All users on Flink 1.20 are strongly recommended to upgrade.

Apache Flink 1.20.4 Release Announcement