detectMultiScale call error

Python
1

Hello,

After calling detectMuliscale function, I get error:

face_cascade.detectMultiScale(image=img_gray, scaleFactor=1.1, minNeighbors=5)
Traceback (most recent call last):
File “<pyshell#12>”, line 1, in
face_cascade.detectMultiScale(image=img_gray, scaleFactor=1.1, minNeighbors=5)
cv2.error: OpenCV(4.5.1) /tmp/pip-req-build-jr1ur_cf/opencv/modules/objdetect/src/cascadedetect.cpp:1689: error: (-215:Assertion failed) !empty() in function ‘detectMultiScale’

Help, please.

Thanks.