elastic/elasticsearch · error · IllegalArgumentException

Expected a LINESTRING, got [{}]

Error message

Expected a LINESTRING, got [{}]

What it means

parseMultiLine (line 743) reads the declared line count, then for each element calls parseGeometry (line 750) and checks instanceof Line (line 751). A non-Line sub-element triggers IllegalArgumentException at line 754. WKB MULTILINESTRING (type 5/1005) must contain only LineString elements.

Source

Thrown at libs/geo/src/main/java/org/elasticsearch/geometry/utils/WellKnownBinary.java:754

                throw new IllegalArgumentException("Expected a " + ShapeType.POINT + ", got [" + geometry.type() + "]");
            }

        }
        return new MultiPoint(Collections.unmodifiableList(points));
    }

    private static MultiLine parseMultiLine(ByteBuffer byteBuffer) {
        final int numLines = byteBuffer.getInt();
        if (numLines == 0) {
            return MultiLine.EMPTY;
        }
        final List<Line> lines = new ArrayList<>(numLines);
        for (int i = 0; i < numLines; i++) {
            final Geometry geometry = parseGeometry(byteBuffer, false);
            if (geometry instanceof Line l) {
                lines.add(l);
            } else {
                throw new IllegalArgumentException("Expected a " + ShapeType.LINESTRING + ", got [" + geometry.type() + "]");
            }
        }
        return new MultiLine(Collections.unmodifiableList(lines));
    }

    private static MultiPolygon parseMultiPolygon(ByteBuffer byteBuffer, boolean coerce) {
        final int numPolygons = byteBuffer.getInt();
        if (numPolygons == 0) {
            return MultiPolygon.EMPTY;
        }
        final List<Polygon> polygons = new ArrayList<>(numPolygons);
        for (int i = 0; i < numPolygons; i++) {
            final Geometry geometry = parseGeometry(byteBuffer, coerce);
            if (geometry instanceof Polygon p) {
                polygons.add(p);
            } else {
                throw new IllegalArgumentException("Expected a " + ShapeType.POLYGON + ", got [" + geometry.type() + "]");
            }

View on GitHub (pinned to db6a809a66)

Solutions

1. Validate producer output against a reference decoder before exchange.
2. Ensure MULTILINESTRING sub-elements carry type code 2 (or 1002 for Z) if you control the producer.
3. Re-serialize from a trusted geometry object via WellKnownBinary.toWKB to normalize.
4. Catch and quarantine corrupt records for offline inspection.

Example fix

// before
Geometry g = WellKnownBinary.fromWKB(v, false, corruptBytes); // throws: Expected a LINESTRING, got [POINT]

// after — re-emit from trusted source
MultiLine ml = new MultiLine(List.of(new Line(new double[]{0,1}, new double[]{0,1})));
byte[] clean = WellKnownBinary.toWKB(ml, ByteOrder.LITTLE_ENDIAN);
Geometry g = WellKnownBinary.fromWKB(v, false, clean);

// No cheap structural pre-check; normalize by re-emitting from trusted source.
byte[] normalize(MultiLine ml) { return WellKnownBinary.toWKB(ml, ByteOrder.LITTLE_ENDIAN); }

// no useful type guard on raw bytes; validate via round-trip

try {
    return WellKnownBinary.fromWKB(v, false, wkb);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Expected a LINESTRING")) {
        // quarantine corrupt MULTILINESTRING record
    }
    throw e;
}

When it happens

Trigger: Calling WellKnownBinary.fromWKB with a MULTILINESTRING WKB whose sub-elements are not LineString-encoded (e.g. Point or Polygon bytes inside the wrapper). Producer bugs, buffer corruption, or endianness misalignment are the usual causes.

Common situations: Interoperability with WKB emitters that allow mixed-type multi-geometries. Truncated/misaligned buffers where a coordinate is misread as a type code. Custom serializers that emit the wrong sub-element type code.

Related errors

• Expected a POINT, got [{}]
• Expected a POLYGON, got [{}]
• Unknown geometry type: {}
• all elements of the collection should have the same number o
• Empty

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/1a4afe41bf9f77d4. Report an issue: GitHub.