Hello there. I'm having a problem with jupyter notebook kernels. Anytime I want to open a python3 kernel I get the following message:

[I 11:49:36.965 NotebookApp] Serving notebooks from local directory: /home/tomaco
[I 11:49:36.965 NotebookApp] The Jupyter Notebook is running at:
[I 11:49:36.965 NotebookApp] http://localhost:8888/?token=f99d04dcf326fd3384ca71c2ccf3d276f7611e6781606ce3
[I 11:49:36.965 NotebookApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 11:49:37.041 NotebookApp]

Copy/paste this URL into your browser when you connect for the first time,
to login with a token:
http://localhost:8888/?token=f99d04dcf326fd3384ca71c2ccf3d276f7611e6781606ce3

[I 11:49:37.254 NotebookApp] Accepting one-time-token-authenticated connection from 127.0.0.1
[I 11:49:44.486 NotebookApp] Creating new notebook in
[E 11:49:44.941 NotebookApp] Uncaught exception GET /notebooks/Untitled14.ipynb?kernel_name=python3 (127.0.0.1)
HTTPServerRequest(protocol='http', host='localhost:8888', method='GET', uri='/notebooks/Untitled14.ipynb?kernel_name=python3', version='HTTP/1.1', remote_ip='127.0.0.1')
Traceback (most recent call last):
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/tornado/web.py", line 1697, in _execute
result = method(*self.path_args, **self.path_kwargs)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/tornado/web.py", line 3174, in wrapper
return method(self, args, **kwargs)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/notebook/notebook/handlers.py", line 59, in get
get_custom_frontend_exporters=get_custom_frontend_exporters
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/notebook/base/handlers.py", line 467, in render_template
return template.render(**ns)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/jinja2/asyncsupport.py", line 76, in render
return original_render(self, args, **kwargs)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/jinja2/environment.py", line 1008, in render
return self.environment.handle_exception(exc_info, True)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/jinja2/environment.py", line 780, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/jinja2/_compat.py", line 37, in reraise
raise value.with_traceback(tb)
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/notebook/templates/notebook.html", line 1, in top-level template code
{% extends "page.html" %}
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/notebook/templates/page.html", line 154, in top-level template code
{% block header %}
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/notebook/templates/notebook.html", line 120, in block "header"
{% for exporter in get_custom_frontend_exporters() %}
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/notebook/notebook/handlers.py", line 19, in get_custom_frontend_exporters
from nbconvert.exporters.base import get_export_names, get_exporter
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/nbconvert/init.py", line 7, in
from . import postprocessors
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/nbconvert/postprocessors/init.py", line 5, in
from .serve import ServePostProcessor
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/nbconvert/postprocessors/serve.py", line 19, in
class ProxyHandler(web.RequestHandler):
File "/home/tomaco/miniconda3/lib/python3.7/site-packages/nbconvert/postprocessors/serve.py", line 21, in ProxyHandler
@web.asynchronous
AttributeError: module 'tornado.web' has no attribute 'asynchronous'
[E 11:49:44.955 NotebookApp] {
"Host": "localhost:8888",
"User-Agent": "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:65.0) Gecko/20100101 Firefox/65.0",
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8",
"Accept-Language": "en-US,en;q=0.5",
"Accept-Encoding": "gzip, deflate",
"Referer": "http://localhost:8888/tree",
"Connection": "keep-alive",
"Cookie": "username-localhost-8888="2|1:0|10:1551797377|23:username-localhost-8888|44:ZDc5OWU4NDFhNmI0NDVjNWE3YjkzMzk0NDRmMTkzMzY=|851786911a4f63b45f1e09e1557a89d9a472955a440c8e9e1bee36541bca676d"; _xsrf=2|137a4b91|1c0aaae8808bc56ccf4a1c8baa098486|1550987614; username-localhost-8889="2|1:0|10:1551795072|23:username-localhost-8889|44:OTBiNTIzNDE0NWRiNDU3MWFkMWVkNDIwZjUxMmU2NzY=|c6be722c2cb2458ea4d172e681d21f7e7465bc0c58f2176da5bd4b47fb03dcab"; username-localhost-8891="2|1:0|10:1551797013|23:username-localhost-8891|44:MmNmMWFkNGU0ZTZiNGIyZTg5ZWMyMzFjY2RlOTIyMGQ=|233aad6377b67251082c48e2552b8ad291287ba0d14867861b23ac6413d88830"; username-localhost-8892="2|1:0|10:1551797270|23:username-localhost-8892|44:M2I0ZTczMWZhM2FmNDExMmEyNDFhMWU1YWVkODdiNzM=|6329346a8532f60ca039bdccb5d41052c6e0906e10200648ee2b791c834a1e2b"",
"Upgrade-Insecure-Requests": "1"
}
[E 11:49:44.955 NotebookApp] 500 GET /notebooks/Untitled14.ipynb?kernel_name=python3 (127.0.0.1) 179.55ms referer=http://localhost:8888/tree

I have installed jupyter notebook with miniconda3 just today. Any ideas?