> I am attempting to upgrade Beam app from 2.5.0 running on Flink
> 1.4.0 to Beam 2.6.0 running on Flink 1.5.0. I am not aware of any
> state migration changes needed for Flink 1.4.0 -> 1.5.0 so I am just
> starting a new App with updated libs from Flink save-point captured
> by previous version of the app.
> There is not change in topology. Job is accepted without error to
> the new cluster which suggests that all operators are matched with
> state based on IDs. However, app runs only few seccons and then
> crash with:
> java.lang.Exception: Exception while creating StreamOperatorStateContext.
> at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:191)
> at org.apache.flink.streaming.api.operators.AbstractStreamOperator.initializeState(AbstractStreamOperator.java:227)
> at org.apache.flink.streaming.runtime.tasks.StreamTask.initializeState(StreamTask.java:730)
> at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:295)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:703)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: org.apache.flink.util.FlinkException: Could not restore operator state backend for DoFnOperator_43996aa2908fa46bb50160f751f8cc09_(1/100) from any of the 1 provided restore options.
> at org.apache.flink.streaming.api.operators.BackendRestorerProcedure.createAndRestore(BackendRestorerProcedure.java:137)
> at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.operatorStateBackend(StreamTaskStateInitializerImpl.java:240)
> at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:139)
> ... 5 more
> Caused by: java.io.IOException: Unable to restore operator state [bundle-buffer-tag]. The previous serializer of the operator state must be present; the serializer could have been removed from the classpath, or its implementation have changed and could not be loaded. This is a temporary restriction that will be fixed in future versions.
> at org.apache.flink.runtime.state.DefaultOperatorStateBackend.restore(DefaultOperatorStateBackend.java:514)
> at org.apache.flink.runtime.state.DefaultOperatorStateBackend.restore(DefaultOperatorStateBackend.java:63)
> at org.apache.flink.streaming.api.operators.BackendRestorerProcedure.attemptCreateAndRestore(BackendRestorerProcedure.java:151)
> at org.apache.flink.streaming.api.operators.BackendRestorerProcedure.createAndRestore(BackendRestorerProcedure.java:123)
> ... 7 more
> Does this mean anything to anyone? Am I doing anything wrong or did
> FlinkRunner change in some way? The mentioned "bundle-buffer-tag"
> seems to be too deep internal in runner for my reach.
> Any help is much appreciated.