I have experienced the incompatible subtype error before. This occurs when, after doing a [source refresh](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/creating_data_sources_and_base_views/source_refresh/source_refresh), you have not updated the [source type properties](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/creating_data_sources_and_base_views/viewing_the_schema_of_a_base_view/viewing_the_schema_of_a_base_view#source-type-properties) to match those of the fields in the underlying data source.
To resolve this, you can:
1. Go to the "Edit" tab of your view.
2. Under "Field Type," click the pencil icon next to the fields marked as red.
3. Specify the source type properties of the field.
Hope this helps!