Error: You must select at least two overlapping line or polygon features
After selecting two overlapping lines and designating a line feature class as the target layer the following error message is returned:
"You must select at least two overlapping line or polygon features and the geometry type of the target layer must match the geometry type of the selected features."
When intersecting line features with the Editor > Intersect command, the two selected lines cross in an X formation.
Solution or Workaround
Use the Editor > Intersect tool when selected line segments have coincident segments which will result in new polyline geometry.
Intersect does not work when the selected lines cross at an X because the common geometry is only an intersection point.