LineString and MultiLineString are not accepted for plots
A LineString is a path, not an area. The EU Information System does not accept LineString or MultiLineString geometries as production places.
What the EU documentation says
The GeoJSON File Description lists the geometry types used for production places (Point, MultiPoint, Polygon, MultiPolygon, and collections of them) and then states: "geometry types of 'LineString' and 'MultiLineString' do not represent valid geocoordinate shapes for declaring production places and will not be accepted/processed." Its common-errors list repeats it: "Invalid geometry types (i.e. LineString)". The DDS API reference lists the supported types as Point, MultiPoint, Polygon, MultiPolygon and GeometryCollection.
Why files contain lines
- Track recording. Many GPS and field apps record a walk as a track (a line). Walking around a field produces a line that follows the boundary, but it's still a line.
- KML exports. KML files from mapping tools often store boundaries as LineStrings or paths.
- Roads and rivers. A file may contain lines that were never meant to be plots: access roads, streams or the edge of a forest drawn for reference.
How to fix it
If the line is a walked boundary and its end comes back to its start, it can become a polygon: use the same coordinates as the outer ring, and make sure the last point equals the first. In QGIS, "Lines to polygons" (Vector, Geometry Tools) does this for a whole layer. Then look at each result on a map to confirm it's really the plot.
If the line doesn't close, the boundary walk was incomplete. Closing it with a straight line may cut through the field or across another edge; re-map instead. See unclosed polygon.
If the line is a road or river, delete it from the upload file. Reference features belong in your own GIS project, not in the DDS geolocation.
What the Plot File Checker does
- LineString or MultiLineString: an error.
- A closed line (its last point is identical to its first, with at least four points) is converted to a Polygon in the fixed file and marked "check this", because the checker can't know whether it was meant to be a boundary.
- A GeometryCollection that contains a line is an error; see GeometryCollection.
- KML Placemarks with LineStrings are read and reported the same way.
For next season
Set your field app to record plots as polygons (or "areas") rather than tracks, if it allows. If it only records tracks, add a step to your process that converts and checks them before the data reaches the exporter.