apache/seatunnel · error · FileConnectorException

DATA_DESERIALIZE_FAILED

DATA_DESERIALIZE_FAILED

Error message

Deserialize this data [%s] failed, please check the origin data

What it means

TextReadStrategy.processLineData deserializes each raw text line per the configured field delimiters/schema; an IOException from the deserializer is wrapped as FileConnectorException(DATA_DESERIALIZE_FAILED) with the offending line. It means one line of the text file did not match the expected row format.

Source

Thrown at seatunnel-connectors-v2/connector-file/connector-file-base/src/main/java/org/apache/seatunnel/connectors/seatunnel/file/source/reader/TextReadStrategy.java:266

                for (int i = 0; i < indexes.length; i++) {
                    fields[i] = seaTunnelRow.getField(indexes[i]);
                }
                seaTunnelRow = new SeaTunnelRow(fields);
            }
            if (isMergePartition) {
                int index = seaTunnelRowType.getTotalFields();
                for (String value : partitionsMap.values()) {
                    seaTunnelRow.setField(index++, value);
                }
            }
            seaTunnelRow.setTableId(tableId);
            output.collect(seaTunnelRow);
        } catch (IOException e) {
            String errorMsg =
                    String.format(
                            "Deserialize this data [%s] failed, please check the origin data",
                            line);
            throw new FileConnectorException(
                    FileConnectorErrorCode.DATA_DESERIALIZE_FAILED, errorMsg, e);
        }
    }

    @Override
    public SeaTunnelRowType getSeaTunnelRowTypeInfo(String path) {
        this.seaTunnelRowType = CatalogTableUtil.buildSimpleTextSchema();
        this.seaTunnelRowTypeWithPartition =
                mergePartitionTypes(getPathForPartitionInference(path), seaTunnelRowType);
        initFormatter();
        if (pluginConfig.hasPath(FileBaseSourceOptions.READ_COLUMNS.key())) {
            throw new FileConnectorException(
                    SeaTunnelAPIErrorCode.CONFIG_VALIDATION_FAILED,
                    "When reading text files, if user has not specified schema information, "
                            + "SeaTunnel will not support column projection");
        }
        ReadonlyConfig readonlyConfig = ReadonlyConfig.fromConfig(pluginConfig);
        TextDeserializationSchema.Builder builder =

View on GitHub (pinned to cf67b549a7)

Solutions

Align the delimiter (field_delimiter) and encoding with the actual file content, inspecting a sample line shown in the error
Fix or skip the malformed line in the source file; check for blank/short lines at file ends
Verify declared field types match the data (e.g. numbers not containing thousand separators)
If the file is CSV with quoting, use the csv read strategy instead of text

Example fix

// before
field_delimiter = ","   // file actually uses tabs
// after
field_delimiter = "\t"  // matches origin data

Defensive patterns

Strategy: try-catch

Validate before calling

// sample first line and compare delimiter counts to declared fields
try (BufferedReader r = Files.newBufferedReader(path, charset)) {
    String line = r.readLine();
    int cols = line.split(Pattern.quote(delimiter), -1).length;
    if (cols != declaredFieldCount)
        throw new IllegalStateException("Delimiter/field mismatch: got " + cols + " expected " + declaredFieldCount);
}

Try / catch

try {
    processLineData(line);
} catch (FileConnectorException e) {
    if (FileConnectorErrorCode.DATA_DESERIALIZE_FAILED.equals(e.getErrorCode())) {
        LOG.warn("Skipping malformed line: {}", line);
    } else throw e;
}

Prevention

Verify field_delimiter and encoding against a file sample before running jobs
Prefer the csv strategy for quoted CSV data instead of text
Declare schema field types that match actual data; strip blank trailing lines

When it happens

Trigger: A line whose field count or content cannot be parsed with the configured delimiter/field types (e.g. delimiter='\t' but file uses ','; quoted fields; empty/extra trailing delimiter; encoding mismatch).

Common situations: Files exported with different delimiters than configured; schema/field-type declarations that don't match data; stray blank lines; mixed encodings; CSV-style quoting inside plain-text delimited files.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/9e49722cae120771. Report an issue: GitHub.