# Kernel error : TypeError: \_kernel\_spec\_manager\_changed()

**URL:** <https://discourse.jupyter.org/t/kernel-error-typeerror-kernel-spec-manager-changed/7490>\
**Category:** The Littlest JupyterHub\
**Tags:** help-wanted\
**Created:** [January 12, 2021, 2:40pm UTC](https://discourse.jupyter.org/t/kernel-error-typeerror-kernel-spec-manager-changed/7490 "2021-01-12T14:40:30Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![philippe7733](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/philippe7733/32/3475_2.png) [@philippe7733](https://discourse.jupyter.org/u/philippe7733)\
**Post date:** [January 12, 2021, 2:40pm UTC](https://discourse.jupyter.org/t/kernel-error-typeerror-kernel-spec-manager-changed/7490/1 "2021-01-12T14:40:30Z")

</div>

I installed tljh on a fresh install of ubuntu server 20.04. The default install of python is 3.8.5 for me. It works fine exept the kernel won’t start with the following error :

> Traceback (most recent call last):  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/web.py”, line 1592, in \_execute  
> result = yield result  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1133, in run  
> value = future.result()  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1141, in run  
> yielded = self.gen.throw(\*exc\_info)  
> File “/opt/tljh/user/lib/python3.7/site-packages/notebook/services/sessions/handlers.py”, line 72, in post  
> type=mtype))  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1133, in run  
> value = future.result()  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1141, in run  
> yielded = self.gen.throw(\*exc\_info)  
> File “/opt/tljh/user/lib/python3.7/site-packages/notebook/services/sessions/sessionmanager.py”, line 88, in create\_session  
> kernel\_id = yield self.start\_kernel\_for\_session(session\_id, path, name, type, kernel\_name)  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1133, in run  
> value = future.result()  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1141, in run  
> yielded = self.gen.throw(\*exc\_info)  
> File “/opt/tljh/user/lib/python3.7/site-packages/notebook/services/sessions/sessionmanager.py”, line 101, in start\_kernel\_for\_session  
> self.kernel\_manager.start\_kernel(path=kernel\_path, kernel\_name=kernel\_name)  
> File “/opt/tljh/user/lib/python3.7/site-packages/tornado/gen.py”, line 1133, in run  
> value = future.result()  
> File “/opt/tljh/user/lib/python3.7/site-packages/notebook/services/kernels/kernelmanager.py”, line 176, in start\_kernel  
> kernel\_id = await maybe\_future(self.pinned\_superclass.start\_kernel(self, \*\*kwargs))  
> File “/opt/tljh/user/lib/python3.7/site-packages/jupyter\_client/multikernelmanager.py”, line 184, in start\_kernel  
> km, kernel\_name, kernel\_id = self.pre\_start\_kernel(kernel\_name, kwargs)  
> File “/opt/tljh/user/lib/python3.7/site-packages/jupyter\_client/multikernelmanager.py”, line 172, in pre\_start\_kernel  
> \*\*constructor\_kwargs  
> File “/opt/tljh/user/lib/python3.7/site-packages/jupyter\_client/multikernelmanager.py”, line 83, in create\_kernel\_manager  
> km = kernel\_manager\_ctor(\*args, \*\*kwargs)  
> File “/opt/tljh/user/lib/python3.7/site-packages/traitlets/config/configurable.py”, line 82, in **init**  
> super(Configurable, self). **init** (\*\*kwargs)  
> File “/opt/tljh/user/lib/python3.7/site-packages/traitlets/traitlets.py”, line 1080, in **init**  
> super\_kwargs[key] = value  
> File “/opt/tljh/user/lib/python3.7/contextlib.py”, line 119, in **exit**  
> next(self.gen)  
> File “/opt/tljh/user/lib/python3.7/site-packages/traitlets/traitlets.py”, line 1214, in hold\_trait\_notifications  
> self.notify\_change(change)  
> File “/opt/tljh/user/lib/python3.7/site-packages/traitlets/traitlets.py”, line 1227, in notify\_change  
> return self.\_notify\_observers(change)  
> File “/opt/tljh/user/lib/python3.7/site-packages/traitlets/traitlets.py”, line 1264, in \_notify\_observers  
> c(event)  
> File “/opt/tljh/user/lib/python3.7/site-packages/traitlets/traitlets.py”, line 888, in compatible\_observer  
> return func(self, change)  
> TypeError: \_kernel\_spec\_manager\_changed() takes 1 positional argument but 2 were given

What am I supposed to do ? Do I have to install another version of python (3.7 ?).

Thanks for your help

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<div class="post-metadata">

**Author:** ![yugankk7](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/yugankk7/32/3499_2.png) [@yugankk7](https://discourse.jupyter.org/u/yugankk7)\
**Post date:** [January 14, 2021, 10:59am UTC](https://discourse.jupyter.org/t/kernel-error-typeerror-kernel-spec-manager-changed/7490/2 "2021-01-14T10:59:14Z")

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Did you find anything to fix this? I have the exact same error.

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<div class="post-metadata">

**Author:** ![philippe7733](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/philippe7733/32/3475_2.png) [@philippe7733](https://discourse.jupyter.org/u/philippe7733)\
**Post date:** [January 14, 2021, 7:57pm UTC](https://discourse.jupyter.org/t/kernel-error-typeerror-kernel-spec-manager-changed/7490/3 "2021-01-14T19:57:24Z")

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I, finaly found a way to make the kernel working.

- I uninstalled tljh according to this procedure : [https://github.com/jupyterhub/the-littlest-jupyterhub/issues/128](https://github.com/jupyterhub/the-littlest-jupyterhub/issues/128)

- I installed python3.7. Do not remove python3.8. I tried and my ssh connection went bad.

- Then I reinstalled tljh with python3.7 instead of python3 in the command line.

Maybe I am lucky and it is not the right solution but my jupyter kernel is working.