Ipython Notebook - ImportError: tornado

Question

I have already updated tornado using

sudo pip install --upgrade tornado

Checking the current version show that I already have a version later than 4.0

Find the output of command:

pip show tornado | grep Version

Metadata-Version: 1.1
Version: 4.1

Any idea why Ipython notebook does not work and keeps giving me the message that i do not have tornado v4.1 and have version 3.0 instead ?. Thanks and Regards.

========================================================================= $ipython notebook

Traceback (most recent call last):
  File "/usr/local/bin/ipython", line 11, in <module>
    sys.exit(start_ipython())
  File "/usr/local/lib/python2.7/dist-packages/IPython/__init__.py", line 120, in start_ipython
    return launch_new_instance(argv=argv, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 573, in launch_instance
    app.initialize(argv)
  File "<string>", line 2, in initialize
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/IPython/terminal/ipapp.py", line 321, in initialize
    super(TerminalIPythonApp, self).initialize(argv)
  File "<string>", line 2, in initialize
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/IPython/core/application.py", line 369, in initialize
    self.parse_command_line(argv)
  File "/usr/local/lib/python2.7/dist-packages/IPython/terminal/ipapp.py", line 316, in parse_command_line
    return super(TerminalIPythonApp, self).parse_command_line(argv)
  File "<string>", line 2, in parse_command_line
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 471, in parse_command_line
    return self.initialize_subcommand(subc, subargv)
  File "<string>", line 2, in initialize_subcommand
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 75, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 402, in initialize_subcommand
    subapp = import_item(subapp)
  File "/usr/local/lib/python2.7/dist-packages/IPython/utils/importstring.py", line 42, in import_item
    module = __import__(package, fromlist=[obj])
  File "/usr/local/lib/python2.7/dist-packages/IPython/html/notebookapp.py", line 50, in <module>
    raise ImportError(msg + ", but you have %s" % tornado.version)
ImportError: The IPython Notebook requires tornado >= 4.0, but you have 3.2

Answer 1

I had a conflicting copy of tornado (3.1.1 on ubuntu 14.04) as well. To see if this is the case for you, in a terminal use the commands:

apt-cache policy python-tornado

To print out the OS's version. If it is not the version you want, use:

sudo apt-get remove python-tornado

to remove it. If you had already installed the newer version using pip, that version will be visible to python now.