Hi Tomas, What's your kafka connector versions? In Kafka-4.0.0[1], the kafka connector is bumped to flink 2.0. (It seems that a version mapping documents about the kafka client & kafka connector & flink version is lacking.
Best, Hongshun [1] https://issues.apache.org/jira/browse/FLINK-36648 On Sun, Sep 28, 2025 at 12:06 PM Shengkai Fang <[email protected]> wrote: > cc @Hongshun > > tomi nader <[email protected]> 于2025年9月18日周四 22:13写道： > >> Hello Flink community, >> >> I am encountering an issue when trying to run a SQL job on *Flink 2.0.0 >> (standalone, macOS)* with a *Kafka sink (Docker).* >> >> *Setup:* >> >> - >> >> Flink 2.0.0 installed locally (~/apps/flink-2.0.0) >> - >> >> Kafka/Zookeeper running via Docker Compose >> - >> >> Job defined in job.sql (5s tumbling window over event time, Kafka >> source and sink) >> >> *Submission command:* >> >> ./sql-client.sh -f ~/flink-lab/sql/job.sql >> >> * Error: * >> >> ClassNotFoundException: org.apache.flink.api.connector.sink2.StatefulSink >> >> >> From what I can tell, this seems like a *compatibility issue between >> Flink 2.0.0 and the Kafka connector JAR*. >> >> *What I have tried so far:* >> >> - >> >> Verified job SQL syntax and configs >> - >> >> Confirmed Flink installation and classpath >> - >> >> Checked the Kafka connector JARs bundled with Flink >> - >> >> Searched documentation and mailing list archives >> >> *Next step I am considering:* downgrading to *Flink 1.19.1*, since it >> appears to be the stable recommended version, while 2.0.0 is still very >> new. But before I take that route, I wanted to ask: >> >> - >> >> Is this a known issue with Flink 2.0.0 and the Kafka connector? >> - >> >> Is there a specific Kafka JAR/connector version that should be used >> with Flink 2.0.0? >> - >> >> Would downgrading to Flink 1.19.1 be the best workaround at this >> point? >> >> Any guidance or confirmation would be greatly appreciated. >> >> Best regards, >> Tomas Nader >> >
