Common Visual Studio Code Issues and Solutions

1. Jupyter Notebook Kernel Fails to Start

The Jupyter Notebook kernel does not start or crashes when executing code.

Root Causes:

  • Incorrect Python interpreter selection in VS Code.
  • Missing or incompatible Jupyter package installation.
  • Conflicts between virtual environments and extensions.

Solution:

Ensure Jupyter is installed in the active Python environment:

pip install jupyter

Select the correct Python interpreter:

Ctrl + Shift + P > Python: Select Interpreter

Restart the Jupyter server:

jupyter notebook --debug

2. VS Code Running Slowly or Freezing

The editor becomes unresponsive or slow, particularly when handling large datasets.

Root Causes:

  • Too many active extensions consuming memory.
  • Large Jupyter notebooks exceeding memory limits.
  • Background processes consuming CPU resources.

Solution:

Disable unnecessary extensions:

Ctrl + Shift + P > Extensions: Show Installed Extensions

Optimize Jupyter Notebook memory usage:

%reset -f

Increase VS Code memory limit:

"files.maxMemoryForLargeFilesMB": 8192

3. Debugging Python Code in VS Code Not Working

Breakpoints do not trigger, or the debugger fails to attach to the process.

Root Causes:

  • Incorrect Python debugging configuration.
  • Virtual environment not detected by VS Code.
  • Conflicts between debugging extensions.

Solution:

Ensure Python debugging is correctly configured in launch.json:

{  "configurations": [    {      "name": "Python: Debug Current File",      "type": "python",      "request": "launch",      "program": "${file}"    }  ]}

Run the debugger manually:

python -m debugpy --listen 5678 --wait-for-client script.py

Ensure the correct virtual environment is activated:

source venv/bin/activate (Mac/Linux)venv\Scripts\activate (Windows)

4. Import Errors When Running Python Code

Python scripts fail to import installed packages inside VS Code.

Root Causes:

  • Wrong Python interpreter selected.
  • Package installed in a different environment.
  • Path conflicts preventing module resolution.

Solution:

Check installed packages in the current environment:

pip list

Explicitly set the Python interpreter in VS Code:

Ctrl + Shift + P > Python: Select Interpreter

Ensure the correct environment is activated before running scripts:

python -m venv myenvsource myenv/bin/activatepip install numpy

5. VS Code Terminal Not Recognizing Python Commands

The integrated terminal fails to recognize Python commands or scripts.

Root Causes:

  • Python not added to system PATH.
  • VS Code using a different shell than expected.
  • Conflicts between system-installed Python and virtual environments.

Solution:

Add Python to system PATH (Windows):

setx PATH "%PATH%;C:\Python39\Scripts\"

Ensure the correct shell is selected in VS Code:

Ctrl + Shift + P > Terminal: Select Default Shell

Use the full path to execute Python scripts:

/usr/bin/python3 script.py

Best Practices for VS Code in Data Science

  • Keep Python and Jupyter extensions updated for compatibility.
  • Use virtual environments to prevent package conflicts.
  • Disable unnecessary extensions to improve performance.
  • Use VS Code’s integrated debugging tools for troubleshooting.
  • Regularly clear Jupyter notebook memory to avoid slowdowns.

Conclusion

By troubleshooting Jupyter kernel failures, performance slowdowns, debugging issues, import errors, and terminal recognition problems, data scientists can optimize their workflow in VS Code. Implementing best practices ensures a smooth and efficient development experience.

FAQs

1. Why is my Jupyter Notebook kernel not starting?

Ensure Jupyter is installed, select the correct interpreter, and restart the Jupyter server.

2. How do I fix VS Code running slowly?

Disable unnecessary extensions, increase memory allocation, and optimize large notebooks.

3. Why is Python debugging not working in VS Code?

Check the debugging configuration, activate the correct environment, and manually attach the debugger.

4. How do I resolve import errors in VS Code?

Select the correct Python interpreter, verify installed packages, and ensure the virtual environment is activated.

5. Why is VS Code terminal not recognizing Python commands?

Add Python to system PATH, select the correct shell, and use the full path to execute scripts.