I installed the Tensorflow(-gpu) version 1.8.0 as a pip package following these instructions. Upon installation, I opened a python3 console and typed in
impo
In fact, this means you have multiple versions of numpy installed somehow (or there are multiple versions that are overlapping). You need to make sure that numpy is fully uninstalled from your system, then reinstall.
For me, I did
pip uninstall numpy
sudo apt-get purge python3-numpy
Then I had to go to /usr/local/lib/python3.6/dist-packages
and delete the numpy folders that were still there for some reason. After that, reinstalling numpy with
pip install numpy
worked. Here is the github issue I opened on it:
https://github.com/numpy/numpy/issues/12775