Visualizer panel is blank

[liyanzhuo2022]

Visualizer panel is blank

Hi, I installed both the official Python extension and this extension.

I clicked "Open Visualizer to the Side" and ran my Python file in the terminal, but the visualizer panel stays empty.

Is there anything else I should do to activate it?

My Setup:

MacOS 14.7.3

Visual Studio Code version: 1.98.2

Python 3.12.4

[jwwylar]

It looks like the issue is related to Python 3.12. When I switched to Python 3.11 or 3.10, the extension worked fine.

Since I'm using Windows, I was able to install multiple versions of Python and change the active version in VS Code by clicking the Python version at the bottom right of the screen.

On macOS, you can try switching to Python 3.11 or 3.10 by doing the following:

1. Install Python 3.11 or 3.10 if you haven’t already (you can download it from python.org).
2. Open VS Code and press Cmd+Shift+P, then search for "Python: Select Interpreter".
3. Choose Python 3.11 or 3.10 from the list.
4. Restart VS Code and see if the issue persists.

Let me know if this works for you!

[FelineAg13]

I'm running into the same issue. installed python and python visualizer, followed all your recommendations and still nada.
my setup
windows 10 pro
vscode 1.98.2
tried python 3.11, 3.10, 3.13, etc..

[jwwylar]

Hi, thanks for the report!

Sometimes the Visualizer panel doesn't load properly the first time due to how VS Code handles webviews. Here’s what to try:

---

✅ What to Do

1. Click “Open Visualizer to the Side” again
   (This is the little purple Python Visualizer logo on the upper right corner of VS Code.)
   If the panel is blank, clicking it again often makes it load correctly on the second try.

2. Make sure you are using a supported Python version.
   Currently, the extension works best with Python 3.10 or 3.11. Python 3.12 or later may cause the visualizer panel to stay blank or not work properly.

   To switch Python versions in VS Code:

   • Press Ctrl+Shift+P (Windows/Linux) or Cmd+Shift+P (Mac) to open the Command Palette.
   • Type and select “Python: Select Interpreter”.
   • Choose Python 3.10 or 3.11 from the list.
   • Restart VS Code and try the visualizer again.

3. Make sure your code is supported by the visualizer. Try this simple program to check:

def bubble_sort(arr):
    n = len(arr)
    for i in range(n):
        for j in range(0, n-i-1):
            if arr[j] > arr[j+1]:
                arr[j], arr[j+1] = arr[j+1], arr[j]

numbers = [5, 3, 8, 2, 1]
bubble_sort(numbers)
print(numbers)

4. Check for error messages in the Output panel:

• Go to View > Output or press Ctrl+Shift+U (Windows) / Cmd+Shift+U (Mac).
• In the dropdown at the top-right of the Output panel, select “Main”.
• Look for any red [error] messages like:

Blocked vscode-webview request ...

• If you see one, copy and paste it here.
• Then try clicking “Open Visualizer to the Side” again — sometimes it works on the second or third try.

---

I’m working on a fix to make the panel more reliable on first load and to support newer Python versions. Thanks again for helping out!