sift = cv2.xfeatures2d.SIFT_create() not working even though have contrib installed

So I am trying to use:

sift = cv2.xfeatures2d.SIFT_create()

and it is coming up with this error:

cv2.error: OpenCV(3.4.3) C:\projects\opencv-python\opencv_contrib\modules\xfeatures2d\src\sift.cpp:1207: error: (-213:The function/feature is not implemented) 
This algorithm is patented and is excluded in this configuration; Set OPENCV_ENABLE_NONFREE CMake 
option and rebuild the library in function 'cv::xfeatures2d::SIFT::create'

I am using Python 3.5.0 and opencv(3.4.3) and I am just using idle. This occured after I tried to install TensorFlow and I have tried looking around and have installed opencv-contrib-python but I am still getting the same error. Thank you in advance and I apologise if I have not included enough info

I had the same problem. It seems that SIRF and SURF are no longer available in opencv > 3.4.2.16. I chose an older opencv-python and opencv-contrib-python versions and solved this problem. Here is the history version about opencv-python, and I use the following code :

pip install opencv-python==3.4.2.16
pip install opencv-contrib-python==3.4.2.16

Edit

For Anaconda User just this instead of pip

conda install -c menpo opencv

this will install cv2 3.4.1 and everything you need to run SIFT

good luck~

Edit: The opencv-contrib-python-nonfree was removed from pypi.

On Linux/ MacOS, I've found a better solution! To access nonfree detectors use: pip install opencv-contrib-python-nonfree

Since SIFT patent expired, SIFT has been moved to the main repo. To use SIFT in Opencv, You should use cv2.SIFT_create() instead of cv2.xfeatures2d.SIFT_create() now. (xfeatures2d only exists in the contrib package, but sift is part of the main package now.)

Below link will be helpful. https://github.com/opencv/opencv/issues/16736