Crash in Intel MKL when debugged via VS Code debugby

jmbjmb — Mon, 26 Jan 2026 23:33:42 GMT

I am running into crashes when trying to use VS Code to debug some Python code that calls Intel MKL. See this debugpy issue for details: https://github.com/microsoft/debugpy/issues/1987. The VS Code Python debugger developers claim it is not an issue with their debugger, but an issue with one of the libraries being called by minimal reproducible example. I don't believe them, but I am doing my due diligence before reopening the issue, starting with MKL as that's the last deepest DLL in the stack trace.

Steps to reproduce:

1) In conda, install this conda environment file

2) In VS Code, set the interpreter to the newly created environment (Ctrl+Shift+P -> Python: Select Interpreter)

3) In VS Code, create a new Python file with the following code:

import numpy as np np.cov(np.random.random(size=(50,41)),rowvar=False) print('hello, world!')

4). Attempt to debug the file (Run and Debug side panel -> ▷ Python Debugger: Current File)

Expected behaviour:

The script prints "hello, world!"

Actual behaviour:

The debugpy process crashes. If I attach a C/C++ debugger to the debugpy process, this is the output:

------------------------------------------------------------------------------ You may only use the C/C++ Extension for Visual Studio Code with Visual Studio Code, Visual Studio or Visual Studio for Mac software to help you develop and test your applications. ------------------------------------------------------------------------------ python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\python.exe'. Symbols loaded. python.exe (27392): Loaded 'C:\Windows\System32\ntdll.dll'. python.exe (27392): Loaded 'C:\Windows\System32\kernel32.dll'. python.exe (27392): Loaded 'C:\Windows\System32\KernelBase.dll'. python.exe (27392): Loaded 'C:\Windows\System32\ucrtbase.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\python312.dll'. Symbols loaded. python.exe (27392): Loaded 'C:\Windows\System32\ws2_32.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\vcruntime140.dll'. python.exe (27392): Loaded 'C:\Windows\System32\version.dll'. python.exe (27392): Loaded 'C:\Windows\System32\rpcrt4.dll'. python.exe (27392): Loaded 'C:\Windows\System32\msvcrt.dll'. python.exe (27392): Loaded 'C:\Windows\System32\bcrypt.dll'. python.exe (27392): Loaded 'C:\Windows\System32\advapi32.dll'. python.exe (27392): Loaded 'C:\Windows\System32\sechost.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\zlib.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Windows\System32\umppc20309.dll'. python.exe (27392): Loaded 'C:\Windows\System32\CsXumd64_20309.dll'. python.exe (27392): Loaded 'C:\Windows\System32\bcryptprimitives.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\python3.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_wmi.pyd'. python.exe (27392): Loaded 'C:\Windows\System32\oleaut32.dll'. python.exe (27392): Loaded 'C:\Windows\System32\msvcp_win.dll'. python.exe (27392): Loaded 'C:\Windows\System32\combase.dll'. python.exe (27392): Loaded 'C:\Windows\System32\propsys.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\vcruntime140_1.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\unicodedata.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_socket.pyd'. python.exe (27392): Loaded 'C:\Windows\System32\IPHLPAPI.DLL'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\select.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_queue.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_decimal.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_ssl.pyd'. python.exe (27392): Loaded 'C:\Windows\System32\crypt32.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Library\bin\libcrypto-3-x64.dll'. Symbols loaded. python.exe (27392): Loaded 'C:\Windows\System32\user32.dll'. python.exe (27392): Loaded 'C:\Windows\System32\win32u.dll'. python.exe (27392): Loaded 'C:\Windows\System32\gdi32.dll'. python.exe (27392): Loaded 'C:\Windows\System32\gdi32full.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Library\bin\libssl-3-x64.dll'. Symbols loaded. python.exe (27392): Loaded 'C:\Windows\System32\imm32.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\pyexpat.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\libexpat.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_bz2.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Library\bin\libbz2.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_lzma.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Library\bin\liblzma.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\DLLs\_ctypes.pyd'. python.exe (27392): Loaded 'C:\Windows\System32\ole32.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Library\bin\ffi-8.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.vscode\extensions\ms-python.debugpy-2025.18.0-win32-x64\bundled\libs\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_cython.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.vscode\extensions\ms-python.debugpy-2025.18.0-win32-x64\bundled\libs\debugpy\_vendored\pydevd\_pydevd_sys_monitoring\_pydevd_sys_monitoring_cython.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Windows\System32\kernel.appcore.dll'. python.exe (27392): Loaded 'C:\Windows\System32\uxtheme.dll'. python.exe (27392): Loaded 'C:\Windows\System32\clbcatq.dll'. python.exe (27392): Loaded 'C:\Windows\System32\amsi.dll'. python.exe (27392): Loaded 'C:\Windows\System32\userenv.dll'. python.exe (27392): Loaded 'C:\Windows\System32\profapi.dll'. python.exe (27392): Loaded 'C:\Windows\System32\ScriptControl64_20309.dll'. python.exe (27392): Loaded 'C:\Windows\System32\mswsock.dll'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\core\_multiarray_umath.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\libcblas.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\mkl_rt.2.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\core\_multiarray_tests.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\linalg\_umath_linalg.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\libblas.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\liblapack.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\fft\_pocketfft_internal.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\mtrand.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\bit_generator.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_common.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\DLLs\_hashlib.pyd'. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_bounded_integers.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_mt19937.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_philox.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_pcg64.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_sfc64.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\unimanual\Lib\site-packages\numpy\random\_generator.cp312-win_amd64.pyd'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\mkl_intel_thread.2.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\mkl_core.2.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\mkl_avx2.2.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\mkl_vml_avx2.2.dll'. Module was built without symbols. python.exe (27392): Loaded 'C:\Users\jmb9770\.conda\envs\test\Library\bin\libiomp5md.dll'. Module was built without symbols. Exception thrown at 0x00007FFD7E6A5369 (KernelBase.dll) in python.exe: 0xC06D007F: Procedure not found (parameters: 0x0000009D74BECF00).

This screenshot shows the stack trace at the time of the crash:

Note that mkl_intel_thread.2.dll is the last DLL called that's not a Windows DLL (i.e. KernelBase.dll), hence why the debugpy developers think it is the culprit.

Additional info:

The script runs fine run as a normal python script, or debugged with pdb.

Environment info:

mkl Version: 2025.3.0 (packaged by conda-forge, build hac47afa_455)
VS Code Version: 1.107.1 (user setup)
Commit: 994fd12f8d3a5aa16f17d42c041e5809167e845a
Date: 2025-12-17T14:15:14.850Z
Electron: 39.2.3
ElectronBuildId: 12895514
Chromium: 142.0.7444.175
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Windows_NT x64 10.0.19045
Python extension version: 2025.20.1
Python Debugger extension version: 2025.18.0
Python Environments extension version 1.14.0
Pylance extension version: 2025.10.4
Python version: 3.12.12
conda version: 24.7.1

Thanks in advance for any help. Please let me know of any other relevant information that I can provide to help diagnose this.

topic Crash in Intel MKL when debugged via VS Code debugby in Intel® oneAPI Math Kernel Library

Crash in Intel MKL when debugged via VS Code debugby