Error: The local edits were not synchronized to the server. Cannot convert polylines or polygons with curves to JSON format
Attempting to synchronize local edits containing true curves from ArcMap to ArcGIS Online displays the following error message:
"The local edits were not synchronized to the server. Cannot convert polylines or polygons with curves to JSON format."
This is a known limitation. The error occurs if the edits contain true curves; a true curve is a curve that only has two vertices as endpoints. Currently, ArcGIS Online does not support true curves created in the geometry of lines and polygons.
Solution or Workaround
In ArcMap, create a local copy of the feature service for editing.
Export the feature service as a shapefile, and save the shapefile to the desired location.
Select and delete all features in the local copy of the feature service.
Copy and paste the features from the shapefile into the local copy.