I got the same error as yours when trying to add rows via REST to a dataset created in Power BI desktop. That seems a limitation and there's already one idea Push data via API into an existing model, you can vote it up.
I got the same error as yours when trying to add rows via REST to a dataset created in Power BI desktop. That seems a limitation and there's already one idea Push data via API into an existing model, you can vote it up.