[Python] ModuleNotFoundError: No module named 'pandas' on Raspberry Pi even after installing...

I’m running a Python project on a Raspberry Pi (Debian / Raspberry Pi OS, Python 3.9.2). The project has its own virtual environment (.venv), and I launch it with a script (alsv4) that starts multiple services using multiprocessing and uvicorn. I did "import pandas as pd" however, this error keeps showing. I am not using it yet but soon I will be. How can this be fixed?

I did "import pandas as pd" however, this error keeps showing. I am not using it yet but soon I will be. How can this be fixed?


Traceback (most recent call last):
File "/usr/lib/python3.9/multiprocessing/process.py", line 315, in _bootstrap
self.run()
File "/usr/lib/python3.9/multiprocessing/process.py", line 108, in run
self._target(*self._args, **self._kwargs)
File "/home/rpi/Desktop/als-v4/main.py", line 32, in run_als_back_service
uvicorn.run("src.services.ALS_back:app", host="0.0.0.0", port=port, reload=False)
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/main.py",
line 580, in run
server.run()
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/server.py",
line 67, in run
return asyncio.run(self.serve(sockets=sockets))
File "/usr/lib/python3.9/asyncio/runners.py", line 44, in run
return loop.run_until_complete(main)
File "/usr/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
return future.result()
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/server.py",
line 71, in serve
await self._serve(sockets)
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/server.py",
line 78, in _serve
config.load()
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/config.py",
line 436, in load
self.loaded_app = import_from_string(self.app)
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/importer.py",
line 22, in import_from_string
raise exc from None
File "/home/rpi/Desktop/als-v4/.venv/lib/python3.9/site-packages/uvicorn/importer.py",
line 19, in import_from_string
module = importlib.import_module(module_str)
File "/usr/lib/python3.9/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 790, in exec_module
File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
File "/home/rpi/Desktop/als-v4/src/services/ALS_back.py", line 4, in <module>
import pandas as pd
ModuleNotFoundError: No module named 'pandas'


I have requirements-rpi.txt.

annotated-types==0.7.0
anyio==4.9.0
certifi==2025.7.14
charset-normalizer==3.4.2
click==8.1.8
exceptiongroup==1.3.0
fastapi==0.116.1
h11==0.16.0
idna==3.10
mfrc522==0.0.7
numpy==2.0.2
opencv-python==4.12.0.88
pillow==11.3.0
pydantic==2.11.7
pydantic-core==2.33.2
python-dotenv==1.1.1
requests==2.32.4
RPi.GPIO==0.7.1
sniffio==1.3.1
spidev==3.7
starlette==0.47.1
typing-extensions==4.14.1
typing-inspection==0.4.1
urllib3==2.5.0
uvicorn==0.35.0
pandas==2.3.2


Context:

Raspberry Pi 4 Model B
PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
NAME="Debian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"
VERSION_CODENAME=bullseye
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

Python 3.9.2
pip 25.2 from /home/rpi/.local/lib/python3.9/site-packages/pip (python 3.9)

Continue reading...