{"record":{"id":"fbfc70647554ce90","repo":"apache/beam","slug":"error-while-processing-the-element-fbfc70","errorCode":null,"errorMessage":"Error while processing the element","messagePattern":"Error while processing the element","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaWriteSchemaTransformProvider.java","lineNumber":156,"sourceCode":"          TupleTag<KV<byte @Nullable [], T>> successTag) {\n        this.conversionFn = conversionFn;\n        this.errorCounter = Metrics.counter(KafkaWriteSchemaTransformProvider.class, name);\n        this.handleErrors = handleErrors;\n        this.errorSchema = errorSchema;\n        this.successTag = successTag;\n      }\n\n      @ProcessElement\n      public void process(@DoFn.Element Row row, MultiOutputReceiver receiver) {\n        KV<byte @Nullable [], T> output = null;\n        try {\n          output = KV.of(null, conversionFn.apply(row));\n        } catch (Exception e) {\n          if (!handleErrors) {\n            throw new RuntimeException(e);\n          }\n          errorsInBundle += 1;\n          LOG.warn(\"Error while processing the element\", e);\n          receiver.get(ERROR_TAG).output(ErrorHandling.errorRecord(errorSchema, row, e));\n        }\n        if (output != null) {\n          receiver.get(successTag).output(output);\n        }\n      }\n\n      @FinishBundle\n      public void finish() {\n        errorCounter.inc(errorsInBundle);\n        errorsInBundle = 0L;\n      }\n    }\n\n    public static class ErrorCounterFn extends BaseKafkaWriterFn<byte[]> {\n      public ErrorCounterFn(\n          String name,\n          SerializableFunction<Row, byte[]> toBytesFn,","sourceCodeStart":138,"sourceCodeEnd":174,"githubUrl":"https://github.com/apache/beam/blob/12126d8942aaf848030c478b4c6a28c6af861c66/sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaWriteSchemaTransformProvider.java#L138-L174","documentation":"KafkaWriteSchemaTransformProvider's ProcessElement wraps row-to-KV conversion in try/catch. When an element fails conversion and error handling is enabled, the exception is not propagated; instead the element is logged at WARN and routed to the error output tag with its error metadata. If handleErrors is false, the exception is rethrown as a RuntimeException and fails the bundle.","triggerScenarios":"conversionFn.apply(row) throws for a specific Row — e.g. a schema field is null where the Kafka serialization expects a value, a payload fails byte conversion, or the row does not match the configured Kafka write schema.","commonSituations":"Pipelines writing malformed or null-bearing rows to Kafka with the error-handling (dead-letter) configuration enabled; developers see the message in logs but some records silently go to the error output instead of the success topic.","solutions":["Inspect the wrapped cause 'e' in the log to find the field/value that failed conversion.","Fix upstream data so rows match the declared write schema (types, nullability).","Consume the ERROR_TAG output of the transform and route those records to a dead-letter sink or repair logic.","If you want the pipeline to fail instead, disable error handling (handleErrors=false) so the exception propagates."],"exampleFix":"// before: errors silently swallowed into ERROR_TAG\n.apply(KafkaWriteSchemaTransformProvider ...)\n// after: handle error records explicitly\nPCollection<Row> errors = result.get(ERROR_TAG);\nerrors.apply(\"DeadLetter\", IO.write(...));","handlingStrategy":"try-catch","validationCode":"if (row.getSchema() != null && row.getValue(\"payload\") == null) {\n  LOG.warn(\"Skipping row with null payload before Kafka write\");\n}","typeGuard":null,"tryCatchPattern":"// Rely on the provider's error output instead of crashing:\nWriteResult result = ...;\nresult.getErrors().apply(\"DeadLetter\", FileIO.write());\n// Or let it fail fast:\n// handleErrors=false -> RuntimeException propagates and fails the bundle","preventionTips":["Validate row schema/nullability before the Kafka write transform.","Always consume ERROR_TAG and route to a dead-letter sink.","Add unit tests with malformed rows to confirm error routing.","Monitor error-record counts in metrics rather than just success output."],"tags":["java","kafka","beam-io","data-quality"],"backgroundTag":"schema-validation-failed","analyzedSha":"12126d8942aaf848030c478b4c6a28c6af861c66","analyzedAt":"2026-09-13T01:50:10.254Z","contentChangedAt":"2026-09-13T01:50:10.254Z","schemaVersion":2},"datasetVersion":"2026-09-14T16:17:12.679Z"}