I also had to downgrade the Jupyter extension to version 2025.6 instead of 2025.7. I have VS Code version 1.103.2 on macOS. After that, the list of Python Environments was loading correctly.
Answer from schneeb on Stack OverflowI also had to downgrade the Jupyter extension to version 2025.6 instead of 2025.7. I have VS Code version 1.103.2 on macOS. After that, the list of Python Environments was loading correctly.
For example I have "Extension" named Python in the image below that gets updated or installed by vsCode automatically
- You have to wait for the "Extensions" to be installed.
- Make sure you have an internet connection.
- make sure you have a fast internet connection so that it can be installed faster.
- After installation restart "vsCode"
If it doesn't work for you, try uninstalling the extension and reinstalling it
This is all I know and it happened to me
Extension Activation failed
Jupyter extension activation fails
Jupyter Extension Activation Failed Can't Run Any Notebook Cells. HELPP
python extension activation failed
Hey everyone,
I'm running into a persistent issue with the Jupyter extension in VS Code and I'm hoping someone can point me in the right direction.
I'm trying to run a simple Python cell in a .ipynb notebook, but I can't execute anything because the Jupyter extension fails to start. As you can see in the screenshot, I keep getting the error notification: Extension activation failed, run the 'Developer: Toggle Developer Tools' command for more information.
What I've Tried So Far:
-
Reinstalling: I have completely uninstalled and reinstalled the Jupyter extension (and its related dependencies like the Python extension) multiple times.
-
Restarts: I have closed and reopened VS Code, and even restarted my computer.
-
New Environments: I've created fresh virtual environments (using
venv) and installedipykernelwithin them, but the issue persists no matter which interpreter I select. -
Different Files: This happens with any notebook file, even a brand new one with a single
print()statement.
I feel like I'm missing something obvious, but I can't figure out what
Hello, I am trying to download the Python extension from Microsoft and it's not working, I am getting this error:
Extension activation failed, run the 'Developer: Toggle Developer Tools' command for more information.
Additionally at the bottom, the spinning "Python extension loading..." just never finishes loading. I'm trying to debug my code and can't, can anyone help? Thank you !
I'm trying to open and execute some ipynb files in Code on Arch Linux. Installed Python and Jupyter extensions.
Whenever I try to run code in the ipnyb file, I get this nagging error message for the Jupyter extension saying
Extension activation failed, run the 'Developer: Toggle Developer Tools' command for more information.
I tried switching the interpreter to the default Python 3.10.2 and also the Python 3.9.x installation in the Anaconda custom environment, but still no luck. Any idea how to fix this?
Please update the python extension to the latest version
or install the pre-release version directly. ( may be more useful to you )
this will basically solve your problem.
If the error continues, follow these steps:
- Uninstall Python extension (if you have pylance uninstall it first). Uninstall any other extension that is failing.
- Close all instances of VS Code.
- Go to, %USERPROFILE%/.vscode/extensions (on windows) or ~/.vscode/extensions on Linux/Mac.
- Delete any folder with the name starting with ms-python.python*
- Start VS Code, and install Python extension (also pylance if you uninstalled it in step 1).
I was having this issue and tried the above answer and it still didn't work. It turns out I hadn't installed python on my system yet. I didn't realize because I normally use it remotely.
From the VSCode documentation:
Quick start
- Step 1. Install a supported version of Python on your system (note: that the system install of Python on macOS is not supported).
- Step 2. Install the Python extension for Visual Studio Code.
- Step 3. Open or create a Python file and start coding!
I had this same issue and finally got it fixed!
If you are on an Linux and are using an Arch-based distro with AUR support, simply install the code-features package using:
yay -S code-features
or any AUR helper of your choosing.
On other operating systems, you should do the following:
Open your VSCode's product.json. I do not know where this file is on your operating system, so please do some research.
Look for the following line:
"extensionAllowedProposedApi": [ ...
Add the following entry to that array:
"ms-toolsai.jupyter": ["notebookConcatTextDocument",
"notebookControllerKind", "notebookDebugOptions", "notebookDeprecated",
"notebookEditor", "notebookEditorDecorationType", "notebookEditorEdit",
"notebookMessaging", "notebookMime", "notebookCellExecutionState",
"portsAttributes", "textDocumentNotebook", "quickPickSortByLabel"]
For example, if the line was originally:
"extensionAllowedProposedApi": [ "extension1", "extension2" ]
Then change it to:
"extensionAllowedProposedApi": [ "extension1", "extension2",
"ms-toolsai.jupyter": ["notebookConcatTextDocument",
"notebookControllerKind", "notebookDebugOptions", "notebookDeprecated",
"notebookEditor", "notebookEditorDecorationType", "notebookEditorEdit",
"notebookMessaging", "notebookMime", "notebookCellExecutionState",
"portsAttributes", "textDocumentNotebook", "quickPickSortByLabel"] ]
Note that with the second method, you will need to edit product.json every time you update VSCode.
Just ran into this today (I'm on MacOS for my work computer). In my case, upgrading to the pre-release version of the Jupyter extension (v2022.5.1001281006) solved it right away.
If you're not an experienced programmer/software engineer, as is the case for me, I suggest trying to upgrade (or roll back) either VS code or the plugin itself before going with your own dev code for the plugin, as with @CAG2 pt2 answer. (Personally, I had trouble finding a 'product.json' file; perhaps you need an insider's build of VS code for that kind of thing [edit]: https://code.visualstudio.com/api/advanced-topics/using-proposed-api, in which case I think you'd be editing 'package.json').