Program generates" ValueError: numpy.dtype size changed, may indicate binary incompatibility. Expected 96 from C header, got 88"

[windy54]

Hi,
I saw your project in the magpi and thought I would demo it at our forthcoming PI Jam.

The program generates the following errors

(pi_classifier) pi@aicam:~/pi_classifier $ python demo.py Traceback (most recent call last): File "/home/pi/pi_classifier/demo.py", line 9, in <module> from picamera2 import CompletedRequest, MappedArray, Picamera2 File "/usr/lib/python3/dist-packages/picamera2/__init__.py", line 11, in <module> from .picamera2 import Picamera2, Preview File "/usr/lib/python3/dist-packages/picamera2/picamera2.py", line 30, in <module> from picamera2.encoders import Encoder, H264Encoder, MJPEGEncoder, Quality File "/usr/lib/python3/dist-packages/picamera2/encoders/__init__.py", line 7, in <module> from .encoder import Encoder, Quality File "/usr/lib/python3/dist-packages/picamera2/encoders/encoder.py", line 12, in <module> from ..request import _MappedBuffer File "/usr/lib/python3/dist-packages/picamera2/request.py", line 13, in <module> import simplejpeg File "/usr/lib/python3/dist-packages/simplejpeg/__init__.py", line 1, in <module> from ._jpeg import encode_jpeg, encode_jpeg_yuv_planes File "simplejpeg/_jpeg.pyx", line 1, in init simplejpeg._jpeg ValueError: numpy.dtype size changed, may indicate binary incompatibility. Expected 96 from C header, got 88 from PyObject (pi_classifier) pi@aicam:~/pi_classifier $
In order to get this far I performed the following steps:

1. installed imx software as per the article

2. I had then had to install opencv which I did in a virtual environment as follows
   python -m venv --system-site-packages pi_classifier so that picamera2 was available within the virtual environment

3. installed opencv using pip install opencv-contrib-python

Not sure what to try to fix it, some suggestions are update numpy and simplejpeg.

How did you set up your environment?

I am using a pi0w2 with the latest release of raspberry pi os, i.e. image created July 26th

great article,

Steve gale

[davidplowman]

Hi, the problem you are having is almost certainly because in Raspberry Pi OS, based on Debian Bookworm, is using numpy 1.24 for all its system packages. Unfortunately many Python users use pip packages which are typically much more bleeding edge and use numpy 2.x. As you've discovered, they're binary incompatible, which has created quite the train wreck in this area.

My best advice is not to install OpenCV from pip. Install the system version from apt (sudo apt install python3-opencv), and it should work fine. Ditto with simplejpeg (sudo apt install python3-simplejpeg). If you've installed pip versions of those, please delete them. You may also need to delete the pip version of numpy 2.x that will likely have been installed (pip uninstall numpy) so that it will fall back to the system 1.24 version.

Unfortunately, Debian packages are always quite far behind the latest versions, and I believe that the next Debian version (Trixie), which will be used for the next Raspberry Pi OS, is still on numpy 1.24. So I can't even promise that this whole numpy disaster is going to get better any time soon. Sorry for all the grief here - but I think we're basically just caught in all the fallout as you are!

[windy54]

Hi davidplowman,Brilliant it works a treat, I re installed opencv as you suggested and then uninstalled numpy so it dropped back to 1.24 and the software just recognised a pi 3.So that is one demo ready for our next PI Jam.CheersSteve GaleOn 28 Jul 2025, at 06:22, davidplowman ***@***.***> wrote:davidplowman left a comment (davidplowman/pi_classifier#1) Hi, the problem you are having is almost certainly because in Raspberry Pi OS, based on Debian Bookworm, is using numpy 1.24 for all its system packages. Unfortunately many Python users use pip packages which are typically much more bleeding edge and use numpy 2.x. As you've discovered, they're binary incompatible, which has created quite the train wreck in this area. My best advice is not to install OpenCV from pip. Install the system version from apt (sudo apt install python3-opencv), and it should work fine. Ditto with simplejpeg (sudo apt install python3-simplejpeg). If you've installed pip versions of those, please delete them. You may also need to delete the pip version of numpy 2.x that will likely have been installed (pip uninstall numpy) so that it will fall back to the system 1.24 version. Unfortunately, Debian packages are always quite far behind the latest versions, and I believe that the next Debian version (Trixie), which will be used for the next Raspberry Pi OS, is still on numpy 1.24. So I can't even promise that this whole numpy disaster is going to get better any time soon. Sorry for all the grief here - but I think we're basically just caught in all the fallout as you are! —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***>