Editing Civil 3D 2019 (section)

=== Profiles ===
Opening an Civil 3D 2019 drawing in Civil 3D 2018

* Fixed vertical curves created with the Fixed Vertical Curve (Parabolic, High/Low Point, Parameter, Length) and Fixed Vertical Curve (Circular, High/Low Point, Parameter, Length) commands are not backward compatible with Civil 3D 2018.
** You can use the Convert Curves command to convert the fixed parabolic curves so they are compatible with Civil 3D 2018, but the fixed circular curves cannot be converted and will be missing when the drawing is opened in AutoCAD Civil 3D 2018.
** If you do not convert the parabolic curves, those curves will also be missing when the drawing is opened in AutoCAD Civil 3D 2018. '''Note:''' Fixed vertical curves created with the Fixed Vertical Curve (Parabolic, High/Low Point, Parameter, Length) command in Autodesk Civil 3D 2019.1 are automatically converted to use two points and a parameter as their constraint type if you open the drawing in AutoCAD Civil 3D 2018. For more information, see the section above.
** After the curves are converted, they cannot be converted back to their original constraint type.

For more information, see [https://help.autodesk.com/view/CIV3D/2019/ENU/?guid=GUID-48BB985A-D671-43E3-81E9-91ADB0FD1BA2 To Change the Constraint Type of Vertical Curves for Backward Compatibility].