Yeah it looks like your BrickPi_Python files, need an update, we have updated our
brickpi_web_server.py and we have resolved this issue in the update. To update your BrickPi_Python folder, run the following commands:
sudo git pull
If the above commands throw an error, then you can update your software by a DI_update following the guide here. This method will erase any specific codes written by you into the BrickPi_Python folder and you will have to save it in a different folder before trying the update.
After updating, run the
Please let us know if this works,