Problem with opencv for robotics course

When I run I get the following error.
What am I doing wrong?

OpenCV Error: Assertion failed (!empty()) in detectMultiScale, file /tmp/binarydeb/ros-kinetic-opencv3-3.3.1/modules/objdetect/src/cascadedetect.cpp, line 1698
[ERROR] [1594801579.399566, 1879.135000]: bad callback: <bound method LoadFace.camera_callback of <main.LoadFace object at 0x7f4e0d88fbd0>>
Traceback (most recent call last):
File “/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/”, line 750, in _invoke_callback
File “/home/user/catkin_ws/src/unit3_exercises/src/”, line 50, in camera_callback
face = face_cascade.detectMultiScale(gray, ScaleFactor, minNeighbors)
error: /tmp/binarydeb/ros-kinetic-opencv3-3.3.1/modules/objdetect/src/cascadedetect.cpp:1698: error: (-215) !empty() in function detectMultiScale

Hello @udo.michelfelder,

Have you downloaded the repository of the course (there are instructions in Unit2 to download it)? I don’t see it in your workspace. I think this is the problem in your case. If you download the repo it should work properly.


Also remember to download it on the proper directory, otherwise it will be automatically deleted by the system once you close the course