Am getting NULL without setting an error on cv2.imwrite

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Here is the full error:

cv2.imwrite(fx,Out_File_Path,[int(cv2.IMWRITE_JPEG_QUALITY), 90])
SystemError: <built-in function imwrite> returned NULL without setting an error

cv2.imshow("",YOLO_image) Works fine.

print(type(YOLO_image))  
print(YOLO_image.dtype)

Gives:

<class 'numpy.ndarray'>
uint8

cv2.imwrite(fx,Out_File_Path,[int(cv2.IMWRITE_JPEG_QUALITY), 90]) and cv2.imwrite(fx,Out_File_Path) both generate the error message shown above.

Windows 10 Pro CV2 Ver 4.20