Python 3.14 and above broke the debug extension

[hellypi]

Environment data

• Python Debugger extension version 2025.8.0

• OS and version: Windows 11

• Python version (& distribution if applicable, e.g. Anaconda): 3.14 (installed using chocolatey)

• Using VS Code or Visual Studio: vsode stable

Error message:

Traceback (most recent call last):
File "c:\Users\Username.vscode\extensions\ms-python.debugpy-2025.8.0-win32-x64\bundled\libs\debugpy_vendored\pydevd_pydevd_sys_monitoring_pydevd_sys_monitoring.py", line 876, in _unwind_event
File "c:\Users\Username.vscode\extensions\ms-python.debugpy-2025.8.0-win32-x64\bundled\libs\debugpy_vendored\pydevd_pydevd_sys_monitoring_pydevd_sys_monitoring.py", line 270, in is_thread_alive
AttributeError: '_MainThread' object has no attribute '_handle'

I found out the problem was with a recent change done with python because of these two tickets:

python/cpython#132578
python/cpython#132789

Indeed, downgrading to python 3.12.10 has allowed me to run the debugger again.

[rchiodo]

This works fine for me in 3.13.3. What version were you using? Sounds like it's changed in 3.14, not 3.13.

[rchiodo]

Yeah, this only crashes for me in 3.14.b01.