Invalid token when trying to login into Jupyter notebook with Docker jupyter/tensorflow-notebook
The answer turned out to be quite easy: there was an other Jupyter notebook server I wasn't aware of running. Closing it did the trick.
I pulled a (seemingly popular, supported by Jupyter) jupyter-tensorflow Docker image using
docker pull jupyter/tensorflow-notebook
and started it successfully with 
docker run -p 8888:8888 jupyter/tensorflow-notebook
However, upon navigating to http://127.0.0.1:8888/?token=177a...., I am prompted for a password or token (despite the token already being present in the URL). 
I know of no password to use, and the token 177a... does not work. 
Any suggestions?