The Apache Flink Community is pleased to announce the first bug fix release of the Flink 2.1 series.
This release includes 25 bug fixes, vulnerability fixes, and minor improvements for Flink 2.1. Below you will find a list of all bugfixes 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 2.1.1 or higher.

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 2.1.1 has been released with 25 bug fixes, vulnerability patches, and minor improvements. Key fixes include resolving NPE issues in RocksDB state backend, fixing checkpoint recovery problems after rescaling with unaligned checkpoints, addressing security vulnerabilities in PyFlink logging, and correcting non-deterministic MAP function behavior with duplicate keys. The release also upgrades dependencies to mitigate CVE-2025-48924 and fixes issues with ForSt state backend data copying during failover.

Apache Flink 2.1.1 Release Announcement