apache/seatunnel · error · RuntimeException

Cannot convert date:

Error message

Cannot convert date: 

What it means

Iceberg RowConverter throws this RuntimeException when a date column value is not a Number (epoch days), LocalDate, or java.util.Date. convertDateValue only handles those representations; other objects (e.g. String, LocalDateTime) are rejected with the raw value in the message.

Source

Thrown at seatunnel-connectors-v2/connector-iceberg/src/main/java/org/apache/seatunnel/connectors/seatunnel/iceberg/data/RowConverter.java:399

            return (ByteBuffer) value;
        }
        throw new IllegalArgumentException(
                "Cannot convert to binary: " + value.getClass().getName());
    }

    protected LocalDate convertDateValue(Object value) {
        if (value instanceof Number) {
            int days = ((Number) value).intValue();
            return DateTimeUtil.dateFromDays(days);
        } else if (value instanceof String) {
            return LocalDate.parse((String) value);
        } else if (value instanceof LocalDate) {
            return (LocalDate) value;
        } else if (value instanceof Date) {
            int days = (int) (((Date) value).getTime() / 1000 / 60 / 60 / 24);
            return DateTimeUtil.dateFromDays(days);
        }
        throw new RuntimeException("Cannot convert date: " + value);
    }

    protected LocalTime convertTimeValue(Object value) {
        if (value instanceof Number) {
            long millis = ((Number) value).longValue();
            return DateTimeUtil.timeFromMicros(millis * 1000);
        } else if (value instanceof String) {
            return LocalTime.parse((String) value);
        } else if (value instanceof LocalTime) {
            return (LocalTime) value;
        } else if (value instanceof Date) {
            long millis = ((Date) value).getTime();
            return DateTimeUtil.timeFromMicros(millis * 1000);
        }
        throw new RuntimeException("Cannot convert time: " + value);
    }

    protected Temporal convertTimestampValue(Object value, Types.TimestampType type) {

View on GitHub (pinned to cf67b549a7)

Solutions

1. Convert the value to LocalDate or epoch-day Number before the sink.
2. Add a transform CAST(column, DATE) so SeaTunnel delivers a proper date value.
3. If the value is a String date, parse it upstream: LocalDate.parse(str).

Example fix

// before
writer.write(idx, "2024-01-15"); // String not accepted
// after
writer.write(idx, LocalDate.parse("2024-01-15")); // LocalDate accepted

if (!(v instanceof Number) && !(v instanceof LocalDate) && !(v instanceof java.util.Date)) throw new IllegalArgumentException("date column must be Number/LocalDate/Date, got " + (v == null ? "null" : v.getClass().getName()));

boolean isDateConvertible(Object v) { return v instanceof Number || v instanceof LocalDate || v instanceof java.util.Date; }

try { sink.write(row); } catch (RuntimeException e) { if (e.getMessage() != null && e.getMessage().startsWith("Cannot convert date")) { /* parse string or DLQ */ } else throw e; }

When it happens

Trigger: convertDateValue receives e.g. a String '2024-01-01', LocalDateTime, or Temporal while mapping to an Iceberg DATE column.

Common situations: String-formatted dates from CSV/JSON sources mapped directly to DATE columns; LocalDateTime values produced for a DATE column after schema change; custom sources returning String dates.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Cannot convert to BigDecimal:
• Cannot convert to boolean:
• Cannot convert to UUID:
• Cannot convert to binary:
• Cannot convert time:

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/49dbf0fc458683ab. Report an issue: GitHub.