Method works as expected on host machine but not on server

[DeaD_EyE]

Description of the error: when updating current_color from within the while loop, I forgot to PARSE again the .ini file, so it didn't update but stayed always the same.

I didn't know that you also want to detect changes.
The configparser object does not have a mechanism to automatically detect changes and reading the file again.

I guess it's better if you put the whole configparser logic into one function.
I introduced some changes and modernized the code.

import time
from configparser import ConfigParser
from datetime import datetime as DateTime
from pathlib import Path

RED = "RED"
TIMECOUNT = Path("timecount.html")
CONFIG = Path("traffic_light.ini")


def get_sign_color(file=CONFIG):
    """
    Return SIGN_COLOR from configuration
    By default, the Path CONFIG is used.
    """
    constants = ConfigParser()
    constants.read(file)
    return constants.get("CONSTANTS", "SIGN_COLOR")


def write_html(counter):
    with TIMECOUNT.open("a") as html_output:
        now = DateTime.now()

        today = now.date()
        hhmmss = now.time().replace(microsecond=0)

        output = f'#"{counter:08d}" | {today} | <b>{hhmmss}</b>\n'
        #"00000010" | 2023-01-05 | <b>11:24:28</b>\n
        html_output.write(output)

    time.sleep(1)


def main():
    counter = 1

    while get_sign_color() != RED:
        write_html(counter)
        counter += 1

    with TIMECOUNT.open("a") as html_output:
        html_output.write(
            '<p><font color="red">Ending cycle from signal "RED".</font></p>\n'
        )


if __name__ == "__main__":
    main()