Operating system: Mint 18
Graphics card: Nvidia 1070
Short description of error
lead into RuntimeError: Error: No other selected objects found to use for projection
Exact steps for others to reproduce the error
Create a plane,
create a Bezier Circle
Select circle and then make plane active object.
Turn into edit mode
F3 + Knife project
-> RuntimeError: Error: No other selected objects found to use for projection.