ValueError: numpy.dtype size changed

How to reproduce the behaviour

Just run doccano webserver --port 8000 and visit localhost:8000.

Your Environment

• Operating System: CachyOS x86_64
• Python Version Used: Python 3.11.11
• When you install doccano: Aug 24, 2025
• How did you install doccano (Heroku button etc): using pipx.

It seems docanno uses pandas<2.0.0,>=1.4.2 but since those pandas do not restrict the numpy so it just uses the newest numpy, that doesn't compatible. The solution is to downgrade numpy. I recommended using numpy below 2.0.0 since this project must not use >2.0.0 version (the latest release is July 2023).

• using pip

pip install "pandas<2.0.0"

• using pipx

pipx runpip doccano install "pandas<2.0.0"