error

[ghost]

[I 19:53:08.853 NotebookApp] The port 8888 is already in use, trying another port.
[I 19:53:08.854 NotebookApp] The port 8889 is already in use, trying another port.
[I 19:53:08.855 NotebookApp] The port 8890 is already in use, trying another port.
[I 19:53:08.855 NotebookApp] The port 8891 is already in use, trying another port.
[W 19:53:08.868 NotebookApp] Error loading server extension jupyter_tensorboard
Traceback (most recent call last):
File "C:\Users\Farnaz Fallahi\Anaconda3\lib\site-packages\notebook\notebookapp.py", line 1573, in init_server_extensions
mod = importlib.import_module(modulename)
File "C:\Users\Farnaz Fallahi\Anaconda3\lib\importlib_init_.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "", line 994, in _gcd_import
File "", line 971, in _find_and_load
File "", line 953, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'jupyter_tensorboard'
[I 19:53:08.902 NotebookApp] JupyterLab extension loaded from C:\Users\Farnaz Fallahi\Anaconda3\lib\site-packages\jupyterlab
[I 19:53:08.902 NotebookApp] JupyterLab application directory is C:\Users\Farnaz Fallahi\Anaconda3\share\jupyter\lab
[I 19:53:08.903 NotebookApp] Serving notebooks from local directory: C:\Users\Farnaz Fallahi
[I 19:53:08.903 NotebookApp] The Jupyter Notebook is running at:
[I 19:53:08.903 NotebookApp] http://localhost:8892/?token=f9c4f48fbad91e30f66623a8a1692021a9e117eb14b62c2f
[I 19:53:08.903 NotebookApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 19:53:08.909 NotebookApp]

Copy/paste this URL into your browser when you connect for the first time,
to login with a token:
http://localhost:8892/?token=f9c4f48fbad91e30f66623a8a1692021a9e117eb14b62c2f
[I 19:53:09.034 NotebookApp] Accepting one-time-token-authenticated connection from ::1
[W 19:53:10.144 NotebookApp] 404 GET /api/tensorboard?_=1552348389578 (::1) 12.96ms referer=http://localhost:8892/tree
[W 19:53:12.479 NotebookApp] 404 POST /api/tensorboard (::1) 1.99ms referer=http://localhost:8892/tree

[robertlugg]

The first fix is to install jupyter_tensorboard:

pip install jupyter-tensorboard

Note the use of dash - versus underscore _ in the above command.

You likely have multiple servers already started based on "The port 8889", etc messages. In a linux shell, type:

ps -U username

, where username above should be yours. Look for and kill any running notebooks which likely are named jupyter using the command kill -9 pid, where pid is the number you see as a result of the ps command

[hgxljy520]

I have another solution, you may have a file named "jupyter_notebook_config.json" in your ".jupyter" dictionary, edit it with this:
{
"NotebookApp": {
"nbserver_extensions": {
"jupyter_tensorboard": false
}
}
}
I have changed this sentence "jupyter_tensorboard": false , the previous was "jupyter_tensorboard": true, just change "true" to "false" and your jupyter notebook will not raise this problem again.