Blender 2.8. Trying to join bezier curve with bezier curve made from spiral: "Cannot make segment" error I created a spiral curve with the spiral curve tool. Then, I added a curve modifier to the spiral curve to make it follow a path. I applied the modifier and deleted the object curve so that the spiral curve remained following the modified path as seen in the image attached.

I am attempting to join the spiral curve to another curve. The first curve is a bezier curve. In Edit mode, I selected the end point of each curve and hit "F" to connect the curves. I got the "Cannot make segement" error.

In edit mode, just to be sure, I went into Curve> Set Spline Type for the spiral curve to bezier. I got the same error.

In the attached image showing the properties window for the objects, you can see that spiral curve is named Spiral.194 under the "num" column in the property chart. It's data type is listed as "Spiral.005". The other curve is named "DNA_Twist.001" and it's data type is listed as "BezierCurve.000.

I'm wondering if, even though I converted the spline type of the spiral curve to bezier, if it won't join the curves because the data types are different? I'm very new to Blender, so any help would be very much appreciated.
There is no way to join 2 curves in Blender. You could convert them both to mesh, join them, and convert back to curves.