Error: OpenCV(4.8.0) /io/opencv/modules/dnn/src/darknet/darknet_io.cpp:660: error: (-215:Assertion failed) separator_index < line.size() in function 'ReadDarknetFromCfgStream'

Python
1 
def saveSeq(C,counter,th):
  op = r'/content/drive/MyDrive/CV/Output'
  if len(C)<th:
    pass
  else:
    k=1
    for frame in C:
      imName = str(counter)+'_'+str(k)+'.jpg'
      final = os.path.join(op,imName)
      box,labels,con = cv.detect_common_objects(frame)
      frame = draw_bbox(frame,box,labels)
      cv2.imwrite(final,frame)
      k+=1

what is this error?? why is this error?