How to install Tensorflow 2.x

follow the link, also show failed.

pip3 install --pre --extra-index-url tensorflow
Looking in indexes: Simple index,
ERROR: Could not find a version that satisfies the requirement tensorflow (from versions: none)
ERROR: No matching distribution found for tensorflow

I also try on Virtual Environment


Which python version do you use?
Please noted that we only support the default python v3.6.