Getting this error - Can anyone assist please?

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Good Morning all,

I was looking for some advice - trying to run a python script utilising opencv 3.4.1 -However I'm getting the below error message. Can anyone help - as I don't know what it means?

"(base) C:\Desktop\python1>python extractfaces.py

OpenCV(3.4.1) Error: Assertion failed (!empty()) in cv::CascadeClassifier::detectMultiScale, file C:\bld\opencv_1520732670222\work\opencv-3.4.1\modules\objdetect\src\cascadedetect.cpp, line 1698
Traceback (most recent call last):
  File "extractfaces.py", line 50, in <module>
    detect_faces(emotion) #Call functiona
  File "extractfaces.py", line 20, in detect_faces
    face = faceDet.detectMultiScale(gray, scaleFactor=1.1, minNeighbors=10, minSize=(5, 5), flags=cv2.CASCADE_SCALE_IMAGE)
cv2.error: OpenCV(3.4.1) C:\bld\opencv_1520732670222\work\opencv-3.4.1\modules\objdetect\src\cascadedetect.cpp:1698: error: (-215) !empty() in function cv::CascadeClassifier::detectMultiScale

Any advice on the above would be much appreciated.

Kind Regards Stephen