apache/flink · error · FlinkRuntimeException

Parquet with case insensitive mode should have no duplicate

Error message

Parquet with case insensitive mode should have no duplicate key: {}

What it means

Error "Parquet with case insensitive mode should have no duplicate key: {}" thrown in apache/flink.

Source

Thrown at flink-formats/flink-parquet/src/main/java/org/apache/flink/formats/parquet/ParquetVectorizedInputFormat.java:214

                            "{} does not exist in {}, will fill the field with null.",
                            fieldName,
                            parquetSchema);
                    types[i] =
                            ParquetSchemaConverter.convertToParquetType(
                                    fieldName, projectedTypes[i], config);
                    unknownFieldsIndices.add(i);
                } else {
                    types[i] = parquetSchema.getType(fieldName);
                }
            }
        } else {
            Map<String, Type> caseInsensitiveFieldMap = new HashMap<>();
            for (Type type : parquetSchema.getFields()) {
                caseInsensitiveFieldMap.compute(
                        type.getName().toLowerCase(Locale.ROOT),
                        (key, previousType) -> {
                            if (previousType != null) {
                                throw new FlinkRuntimeException(
                                        "Parquet with case insensitive mode should have no duplicate key: "
                                                + key);
                            }
                            return type;
                        });
            }
            for (int i = 0; i < projectedFields.length; ++i) {
                Type type =
                        caseInsensitiveFieldMap.get(projectedFields[i].toLowerCase(Locale.ROOT));
                if (type == null) {
                    LOG.warn(
                            "{} does not exist in {}, will fill the field with null.",
                            projectedFields[i],
                            parquetSchema);
                    type =
                            ParquetSchemaConverter.convertToParquetType(
                                    projectedFields[i].toLowerCase(Locale.ROOT),
                                    projectedTypes[i],

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Address the cause reported by the error message: Parquet with case insensitive mode should have no duplicate key: the reported value
2. Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry.

Example fix

Correct the condition described ("Parquet with case insensitive mode should have no duplicate key: the reported value") and rerun the job or command.

When it happens

Trigger: Triggered at runtime when the operation fails because: Parquet with case insensitive mode should have no duplicate key: the reported value.

Common situations: Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Parquet with case insensitive mode should have no duplicate key: the reported value.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/075e508064cdb7da. Report an issue: GitHub.