Jupyter Lab and Notebook Problem: Kernel Error
Question:
It appears that somehow one of my kernels is deleted. And perhaps that’s why I am getting this error. How could I possibly fix it? Can I reinstall something (the kernel in the base environment perhaps)?
If no better option is available, I would try reinstalling anaconda altogether as a last resort according to: Default kernel in jupyter notebook (Python3) not working.
I have tried using the following:
- Installation of Jupyter Lab:
requirements already satisfied
- Kernels don’t show up when runnning “jupyter lab”
- UI says “No kernel” while I definitively have one
- Getting Kernel Error while running Jupyter Notebook in Python3
- https://ipython.readthedocs.io/en/latest/install/kernel_install.html
- https://medium.com/flatiron-engineering/recovering-from-a-jupyter-disaster-27401677aeeb
Current List of Kernels
jupyter kernelspec list
Output:
Available kernels:
python3 C:UsersraysuAppDataRoamingjupyterkernelspython3
vpython C:ProgramDatajupyterkernelsvpython
But I must have another kernel (which I suppose somehow got deleted) associated with my base environment.
C:UsersraysuDocuments>conda env list
# conda environments:
#
base * C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64
astra_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envsastra_env
bokeh_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envsbokeh_env
sound_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envssound_env
tf_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envstf_env
C:UsersraysuAnaconda3
C:UsersraysuAnaconda3envspyforge
opencv_env C:UsersraysuAppDataLocalcondacondaenvsopencv_env
test_env C:UsersraysuAppDataLocalcondacondaenvstest_env
Error
Traceback (most recent call last):
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadoweb.py", line 1699, in _execute
result = await result
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 742, in run
yielded = self.gen.throw(*exc_info) # type: ignore
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookservicessessionshandlers.py", line 72, in post
type=mtype))
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 735, in run
value = future.result()
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 742, in run
yielded = self.gen.throw(*exc_info) # type: ignore
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookservicessessionssessionmanager.py", line 88, in create_session
kernel_id = yield self.start_kernel_for_session(session_id, path, name, type, kernel_name)
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 735, in run
value = future.result()
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 742, in run
yielded = self.gen.throw(*exc_info) # type: ignore
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookservicessessionssessionmanager.py", line 101, in start_kernel_for_session
self.kernel_manager.start_kernel(path=kernel_path, kernel_name=kernel_name)
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 735, in run
value = future.result()
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 209, in wrapper
yielded = next(result)
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookserviceskernelskernelmanager.py", line 168, in start_kernel
super(MappingKernelManager, self).start_kernel(**kwargs)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientmultikernelmanager.py", line 110, in start_kernel
km.start_kernel(**kwargs)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientmanager.py", line 240, in start_kernel
self.write_connection_file()
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientconnect.py", line 476, in write_connection_file
kernel_name=self.kernel_name
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientconnect.py", line 141, in write_connection_file
with secure_write(fname) as f:
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libcontextlib.py", line 81, in __enter__
return next(self.gen)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_corepaths.py", line 404, in secure_write
win32_restrict_file_to_user(fname)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_corepaths.py", line 359, in win32_restrict_file_to_user
import win32api
ImportError: DLL load failed: The specified procedure could not be found.
Answers:
Solved the problem by editing the relevant kernelspec: kernel.json file after fresh installation of Anaconda.
Solution in Detail
As reported earlier, I found that I had two kernelspecs. (command: jupyter kernelspec list)
- python3:
C:UsersraysuAppDataRoamingjupyterkernelspython3
- vpython:
C:ProgramDatajupyterkernelsvpython
The kernelspec is a .json file that maintains kernel-specifications for jupyter-notebook/lab to launch a certain kernel. Fortunately, the kernel vpython was functioning and that helped me narrow down the source of the problem located inside kernelpsec: python3. I had to correct the path to the python executable (python.exe) and that solved the issue.
I would like to mention that in this case the following two resources came handy. I got more clarity in where the problem could be, after I saw the typical-structure of the kernelspec document.
Note: However, since I cannot test this theory, I would ask anyone else in a similar problem, to first make a copy of the old kernel.json file and then update the path to python.exe file. If that resolves the kernel error, then reinstalling Anaconda altogether may not be necessary.
Long story short:
If your jupyter notebook/lab environment shows you kernel error, most likely the source of the problem is inside the kernelspec file: kernel.json and the path to python.exe is incorrect. This could be a more likely scenario, if the same kernel error persists even after fresh re-installation of anaconda/jupyter-notebook/lab.
For instance, in my case, the python3-kernelspec was located at:
"C:UsersraysuAppDataRoamingjupyterkernelspython3"
And the python.exe was located at:
"C:UsersraysuAnaconda3python.exe"
However, the path to the python-executable was wrong: it was still showing the path from the old installation. And post-anaconda-reinstallation, this path had changed. So, I had to update the kernelspec for python3 by editing kernel.json file.
# kernel.json file
{
"argv": [
"C:\Users\raysu\Anaconda3\python.exe",
"-m",
"ipykernel_launcher",
"-f",
"{connection_file}"
],
"display_name": "Python 3",
"language": "python"
}
If this does not solve your problem, please consult the following two documents. I wasted 4 days because of this. Hopefully, this answer would help out someone in future.
What came handy?
I was able to resolve the problem
here
I installed jupyter_client 5.3.4 and jupyter_core 4.6.0 with this command
pip install jupyter_client --upgrade
The most upvoted answer is correct even when you are getting [Winerror 2] just like me. Go to the kernel json and change the path to the Anaconda3 python.exe and problem will be most likely solved.
It appears that somehow one of my kernels is deleted. And perhaps that’s why I am getting this error. How could I possibly fix it? Can I reinstall something (the kernel in the base environment perhaps)?
If no better option is available, I would try reinstalling anaconda altogether as a last resort according to: Default kernel in jupyter notebook (Python3) not working.
I have tried using the following:
- Installation of Jupyter Lab:
requirements already satisfied - Kernels don’t show up when runnning “jupyter lab”
- UI says “No kernel” while I definitively have one
- Getting Kernel Error while running Jupyter Notebook in Python3
- https://ipython.readthedocs.io/en/latest/install/kernel_install.html
- https://medium.com/flatiron-engineering/recovering-from-a-jupyter-disaster-27401677aeeb
Current List of Kernels
jupyter kernelspec list
Output:
Available kernels:
python3 C:UsersraysuAppDataRoamingjupyterkernelspython3
vpython C:ProgramDatajupyterkernelsvpython
But I must have another kernel (which I suppose somehow got deleted) associated with my base environment.
C:UsersraysuDocuments>conda env list
# conda environments:
#
base * C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64
astra_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envsastra_env
bokeh_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envsbokeh_env
sound_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envssound_env
tf_env C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64envstf_env
C:UsersraysuAnaconda3
C:UsersraysuAnaconda3envspyforge
opencv_env C:UsersraysuAppDataLocalcondacondaenvsopencv_env
test_env C:UsersraysuAppDataLocalcondacondaenvstest_env
Error
Traceback (most recent call last):
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadoweb.py", line 1699, in _execute
result = await result
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 742, in run
yielded = self.gen.throw(*exc_info) # type: ignore
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookservicessessionshandlers.py", line 72, in post
type=mtype))
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 735, in run
value = future.result()
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 742, in run
yielded = self.gen.throw(*exc_info) # type: ignore
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookservicessessionssessionmanager.py", line 88, in create_session
kernel_id = yield self.start_kernel_for_session(session_id, path, name, type, kernel_name)
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 735, in run
value = future.result()
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 742, in run
yielded = self.gen.throw(*exc_info) # type: ignore
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookservicessessionssessionmanager.py", line 101, in start_kernel_for_session
self.kernel_manager.start_kernel(path=kernel_path, kernel_name=kernel_name)
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 735, in run
value = future.result()
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagestornadogen.py", line 209, in wrapper
yielded = next(result)
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libsite-packagesnotebookserviceskernelskernelmanager.py", line 168, in start_kernel
super(MappingKernelManager, self).start_kernel(**kwargs)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientmultikernelmanager.py", line 110, in start_kernel
km.start_kernel(**kwargs)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientmanager.py", line 240, in start_kernel
self.write_connection_file()
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientconnect.py", line 476, in write_connection_file
kernel_name=self.kernel_name
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_clientconnect.py", line 141, in write_connection_file
with secure_write(fname) as f:
File "C:Program Files (x86)Microsoft Visual StudioSharedAnaconda3_64libcontextlib.py", line 81, in __enter__
return next(self.gen)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_corepaths.py", line 404, in secure_write
win32_restrict_file_to_user(fname)
File "C:UsersraysuAppDataRoamingPythonPython36site-packagesjupyter_corepaths.py", line 359, in win32_restrict_file_to_user
import win32api
ImportError: DLL load failed: The specified procedure could not be found.
Solved the problem by editing the relevant
kernelspec:kernel.jsonfile after fresh installation of Anaconda.
Solution in Detail
As reported earlier, I found that I had two kernelspecs. (command: jupyter kernelspec list)
- python3:
C:UsersraysuAppDataRoamingjupyterkernelspython3 - vpython:
C:ProgramDatajupyterkernelsvpython
The kernelspec is a .json file that maintains kernel-specifications for jupyter-notebook/lab to launch a certain kernel. Fortunately, the kernel vpython was functioning and that helped me narrow down the source of the problem located inside kernelpsec: python3. I had to correct the path to the python executable (python.exe) and that solved the issue.
I would like to mention that in this case the following two resources came handy. I got more clarity in where the problem could be, after I saw the typical-structure of the kernelspec document.
Note: However, since I cannot test this theory, I would ask anyone else in a similar problem, to first make a copy of the old kernel.json file and then update the path to python.exe file. If that resolves the kernel error, then reinstalling Anaconda altogether may not be necessary.
Long story short:
If your jupyter notebook/lab environment shows you kernel error, most likely the source of the problem is inside the kernelspec file: kernel.json and the path to python.exe is incorrect. This could be a more likely scenario, if the same kernel error persists even after fresh re-installation of anaconda/jupyter-notebook/lab.
For instance, in my case, the python3-kernelspec was located at:
"C:UsersraysuAppDataRoamingjupyterkernelspython3"
And the python.exe was located at:
"C:UsersraysuAnaconda3python.exe"
However, the path to the python-executable was wrong: it was still showing the path from the old installation. And post-anaconda-reinstallation, this path had changed. So, I had to update the kernelspec for python3 by editing kernel.json file.
# kernel.json file
{
"argv": [
"C:\Users\raysu\Anaconda3\python.exe",
"-m",
"ipykernel_launcher",
"-f",
"{connection_file}"
],
"display_name": "Python 3",
"language": "python"
}
If this does not solve your problem, please consult the following two documents. I wasted 4 days because of this. Hopefully, this answer would help out someone in future.
What came handy?
I was able to resolve the problem
here
I installed jupyter_client 5.3.4 and jupyter_core 4.6.0 with this command
pip install jupyter_client --upgrade
The most upvoted answer is correct even when you are getting [Winerror 2] just like me. Go to the kernel json and change the path to the Anaconda3 python.exe and problem will be most likely solved.