Python 3.14 - Failed to find python version from target process

[MaxG87]

First of all, thank you very much for this interesting project. I was looking for an all-in-one flame graph generator and this project looks like it is a very good fit for my needs. Unfortunately, I was unable to use it, though.

I am on CachyOS, an Arch Linux derivate, with Python 3.14. I installed py-spy from AUR and have version 0.4.1.

Running py-spy as suggested in the README yields an error:

$ py-spy --version
py-spy 0.4.1
$ py-spy record -o primes.svg -- python primes.py
Error: Failed to find python version from target process
$ sudo py-spy record -o primes.py.svg -- python primes.py
Error: Failed to find python version from target process

Since this kind of error was reported a few times and often had to be addressed with a fix, I hope reporting it again is the right thing to do here. If I am using py-spy the wrong way, I'd appreciate some helpful hint.

Thank you for all the effort.

[MaxG87]

I think I the issue comes from an incompatibility of py-spy and Python 3.14.

I tried to run py-spy in a Docker container. The file will be at the end. If the base image is python:3.13-slim, I can start the profiling. However, when using python:3.14-slim I get the exact same error message as reported in the first message.

FROM python:3.13-slim

RUN python -m pip install --no-cache-dir py-spy
WORKDIR /app
COPY . .

CMD ["py-spy", "record", "-o", "profile.svg", "--", "python", "primes.py"]

[Kataglyphis]

have the same problem and the same conclusion 👍
There are already some issues open related to this.
F.e. issue 750

[All-The-Foxes]

Same here. I cannot run py-spy on processes running Python 3.14.

[alexchandel]

Replicated on Python 3.14.3. Possibly related to 3.14's new remote debugger support?

[alexchandel]

Looks like this is blocked by #819, may be abandoned

[Dadaskis]

I mentioned that it doesn't work on Arch with Python 3.14 here too
#397 (comment)

I can confirm on my end that it is not working on Python 3.14 in both Windows and Linux

[charles-dyfis-net]

With python/cpython#146462, all the prerequisites for supporting 3.15+ without bindgen will be met (and I suspect I can get a suitable workaround together for 3.14).

[kerrickstaley]

This was fixed in py-spy 0.4.2. (This issue is a dupe of #750).

[dineshbvadhia]

Python 3.14.6
Windows 11 with latest updates
py-spy 0.4.2

Doesn't work. Error message as above ie.
Error: Failed to find python version from target process

[laundmo]

I was still getting this error in py-spy 0.4.2, the fix was running:
sudo setcap cap_sys_ptrace=eip "$(realpath "$(which py-spy)")"
before py-spy. That gives py-spy the required perms. After that it just worked.

Would be cool if py-spy could detect its missing the capabilities and log a proper error, perhaps with this recommendation.