{"record":{"id":"30717c6b5a0288a8","repo":"apache/iceberg","slug":"failed-to-initialize-serializercache-for-reading-d-30717c","errorCode":null,"errorMessage":"Failed to initialize serializerCache for reading data with old serializer","messagePattern":"Failed to initialize serializerCache for reading data with old serializer","errorType":"exception","errorClass":"RuntimeException","httpStatus":null,"severity":"error","filePath":"flink/v2.2/flink/src/main/java/org/apache/iceberg/flink/sink/dynamic/DynamicRecordInternalSerializer.java","lineNumber":334,"sourceCode":"    @Override\n    public TypeSerializerSchemaCompatibility<DynamicRecordInternal> resolveSchemaCompatibility(\n        TypeSerializerSnapshot<DynamicRecordInternal> oldSerializerSnapshot) {\n      if (oldSerializerSnapshot.getCurrentVersion() == getCurrentVersion()) {\n        return TypeSerializerSchemaCompatibility.compatibleAsIs();\n      }\n\n      // Old TypeSerializerSnapshots do not contain the serializer cache, but the newest one does.\n      // This will also ensure that we always use the up-to-date cache alongside with its catalog\n      // configuration.\n      Preconditions.checkNotNull(serializerCache, \"serializerCache should not be null\");\n      try {\n        DynMethods.builder(\"initializeSerializerCache\")\n            .hiddenImpl(\n                DynamicRecordInternalTypeSerializerSnapshot.class, TableSerializerCache.class)\n            .build()\n            .invoke(oldSerializerSnapshot, serializerCache);\n      } catch (Exception e) {\n        throw new RuntimeException(\n            \"Failed to initialize serializerCache for reading data with old serializer\", e);\n      }\n\n      // This will first read data with the old serializer, then switch to the most recent one.\n      return TypeSerializerSchemaCompatibility.compatibleAfterMigration();\n    }\n\n    @Override\n    public TypeSerializer<DynamicRecordInternal> restoreSerializer() {\n      if (getCurrentVersion() < MOST_RECENT_VERSION) {\n        // If this serializer is not the most recent one, we need to read old data with the correct\n        // parameters.\n        return new DynamicRecordInternalSerializer(serializerCache, writeSchemaAndSpec, false);\n      }\n\n      // In all other cases, we just use the newest serializer.\n      return new DynamicRecordInternalSerializer(serializerCache, writeSchemaAndSpec, true);\n    }","sourceCodeStart":316,"sourceCodeEnd":352,"githubUrl":"https://github.com/apache/iceberg/blob/86d9c8fc543e7c56c9f624eb725f76c9baff9570/flink/v2.2/flink/src/main/java/org/apache/iceberg/flink/sink/dynamic/DynamicRecordInternalSerializer.java#L316-L352","documentation":"In DynamicRecordInternalSerializer.resolveSchemaCompatibility, when restoring serializer state written by an old snapshot format, the code reflectively invokes the hidden initializeSerializerCache method on DynamicRecordInternalTypeSerializerSnapshot. Any reflection failure is wrapped in a RuntimeException with this message, so old-version data cannot be read for migration.","triggerScenarios":"Restoring from a checkpoint/savepoint written by an older Iceberg-Flink release whose DynamicRecordInternalTypeSerializerSnapshot layout differs, causing the hidden-method invocation (or cache initialization) to fail — seen in testRestoreFromOldVersion scenarios.","commonSituations":"Cross-version upgrades (e.g. 1.9 -> 2.x) where the internal snapshot class changed; jars on the classpath mixing old and new iceberg-flink classes.","solutions":["Align the iceberg-flink runtime version used at restore time with the version that wrote the checkpoint, or use a version that supports migration from it.","Ensure only one consistent iceberg-flink jar is on the classpath (no shaded duplicates).","If the old checkpoint cannot be migrated, start a new job without state and let the sink rewrite in-flight data."],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":"// verify class presence and consistent jars before restore\nClass.forName(\"org.apache.iceberg.flink.sink.dynamic.DynamicRecordInternalTypeSerializerSnapshot\");","typeGuard":null,"tryCatchPattern":"try { compat = serializer.resolveSchemaCompatibility(oldSnapshot); } catch (RuntimeException e) { if (e.getMessage().contains(\"Failed to initialize serializerCache\")) { /* plan full restart without state or with matching versions */ } throw e; }","preventionTips":["Keep a single consistent iceberg-flink jar on the classpath","Upgrade in supported migration steps, not across many versions at once","Test checkpoint restores from the previous release before upgrading"],"tags":["flink","serialization","compatibility"],"backgroundTag":"incompatible-source-type","analyzedSha":"86d9c8fc543e7c56c9f624eb725f76c9baff9570","analyzedAt":"2026-09-12T00:46:39.097Z","contentChangedAt":"2026-09-12T00:46:39.097Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}