I have merged two vectors layers. When I try to merge two features - originally from two different source layers, now in the Merged layer - I get this error:

Layer Merged: Geometry type MultiPolygon not compatible with provider type Polygon.

I'm not sure how to solve this.

1) To begin with, how can I successfully merge two layers if they have different geometry types?

2) In my case, how to understand which source layer is considered by QGIS as a MultiPolygon and which on is a Polygon. In their Properties -> Metadata -> Properties -> Geometry type of the features in this layer they both appear as Polygon (WKB type: "Polygon").

3) How to manipulate the layers so to successfully merged features from the two source layers?

  • 1
    What format is your vector in that you're trying to merge with? It sounds like your data type doesn't support multipolygon types (multi part polygons) but only single exterior ring and holes.. perhaps you could merge into shapefile then export into your desired format later, when all the edits are done. Commented Dec 11, 2017 at 4:56

1 Answer 1


You can use the "Singleparts to multipart" tool to convert your Polygons to multipolygons before merging to avoid this conflic. Make shure you set a unique ID as "Unique ID field" to avoid your polygons from getting merged.

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