Error in Face Recognition code

can any one tell me what to do? i am receiving this error. How to resolve it?

recognizer.read('trainer/trainer.yml')
cv2.error: OpenCV(4.1.0) C:\projects\opencv-python\opencv_contrib\modules\face\src\facerec.cpp:61: error: (-2:Unspecified error) File can't be opened for reading! in function 'cv::face::FaceRecognizer::read'
