JupyterLab on Windows does not properly activate conda environment

[ukoethe]

This might be related to #381 and #386.

After installation on Windows, I got the "Server Initialization Error" reported in #381 with same log message. I was able to work around the problem by starting jlab from the command line after explicit activation of the Python environment:

C:\Users\ukoethe> C:\JupyterLab\resources\jlab_server\condabin\activate
(base) C:\Users\ukoethe> jlab .

The same was necessary in order to use a custom Python environment. Merely adding the path to the Python environment as described here is not sufficient! Once again, the environment must first be activated, e.g.:

C:\Users\ukoethe> activate my_env   # assuming conda is in the PATH
(my_env) C:\Users\ukoethe> jlab .

On Windows, the activate command adds about 7 directories to the PATH variable, and jupyter will not work properly without these settings. The workaround suggested in #381 (comment) (copy some DLLs to other directories) is not the correct solution.

I suggest to add the appropriate activate call at the beginning of JupyterLab.exe.

On a related note, in some cases the JupyterLab GUI opened, but was unable to start the kernel. After some time-out period, the status bar displayed Python 3 | Disconnected. Then, running a cell had no effect except for advancing to the next cell, as described in #386. Once again, activating the environment properly before running JupyterLab fixed this problem.

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[krassowski]

Thank you @ukoethe this is a very valuable observation. I really appreciate you taking time to experiment and figure out the problem and the solution.

[aravindh-krishnamoorthy]

I can confirm that the solution in the OP works.

Installation version: v3.2.5-2 installed via the Windows Installer
Options: Just me + Installation directory: C:\JupyterLab

Initially, I could not start JupyterLab Desktop due to #381. Then, I followed the instructions in the OP (I have no custom Python installation):

C:\Users\ukoethe> C:\JupyterLab\resources\jlab_server\condabin\activate
(base) C:\Users\ukoethe> jlab .

Now, JupyterLab Desktop opens.

[yellowincarnate]

I also agree that this workaround works - I'm part of a class that is learning to code for the first time, and the CMD Line solution does work, it's also hard for many of my classmates to understand/work with. Hopefully there's a way to integrate this?

[MichaDit]

Seems both issues "Server Initialization Error" and "Cannot connect to Kernel" originate from same source.
This solved both problems for v3.2.5-2 installed via the Windows Installer.
Both issues are independent of option current user/all users choosen within install.

My hack is to execute jlab from this file now (save as JupyterLab.bat):

CALL C:\JupyterLab\resources\jlab_server\condabin\activate
start C:\JupyterLab\JupyterLab.exe

[antunderwood]

The solution by @MichaDit represents a good way to be able to have a file that is clickable to launch JupyerLab. 👍

Seems both issues "Server Initialization Error" and "Cannot connect to Kernel" originate from same source. This solved both problems for v3.2.5-2 installed via the Windows Installer. Both issues are independent of option current user/all users choosen within install.

My hack is to execute jlab from this file now (save as JupyterLab.bat):

CALL C:\JupyterLab\resources\jlab_server\condabin\activate
start C:\JupyterLab\JupyterLab.exe

[ukoethe]

The solution by @MichaDit represents a good way to be able to have a file that is clickable to launch JupyerLab.

Indeed, and that's also what I do right now. But including the activation into JupyterLab.exe itself would be preferable.

[mbektas]

@ukoethe @MichaDit @antunderwood @yellowincarnate @aravindh-krishnamoorthy could you test the v3.2.9-1 release candidate for this issue? https://github.com/jupyterlab/jupyterlab-desktop/releases/tag/v3.2.9-1

[MichaDit]

@ukoethe @MichaDit @antunderwood @yellowincarnate @aravindh-krishnamoorthy could you test the v3.2.9-1 release candidate for this issue? https://github.com/jupyterlab/jupyterlab-desktop/releases/tag/v3.2.9-1

Besides missing installer signature, everything seems to work fine on Win10.
Thx for providing the update (and JLab Desktop as a whole) @mbektas!

Edit: Sometimes there is JS error on start and JLab cannot connect to kernel:

[mbektas]

thanks for testing @MichaDit! Are you getting that JS error randomly or do you have steps to reproduce?

[MichaDit]

Randomly, cannot figure out any steps to reproduce @mbektas

[mbektas]

thanks @MichaDit. I was also able to reproduce randomly and have been debugging this issue for days. The server appears to be crashing when making websocket connections, but I couldn't trace the source of the crash (checked available logs and call stacks). It happens only at initial launch time and only when server is launched from the electron app. I couldn't find the source of the crash but as a remedy I am restarting the server if it crashes. Once you get the error as in #388 (comment), you can restart the kernel now.

[mbektas]

@ukoethe could you test with the latest version and update the issue if it fixes the problem or not? https://github.com/jupyterlab/jupyterlab-desktop/releases/tag/v3.3.2-1

[mbektas]

closing since no response for long. please retest with latest and create new issue if necessary.