dgtlmoon/changedetection.io · warning · ValueError

Invalid timezone_str: '{timezone_str}'. Must be a valid time

Error message

Invalid timezone_str: '{timezone_str}'. Must be a valid timezone identifier.

What it means

ValueError raised by am_i_inside_time when arrow.now(timezone_str.strip()) throws — i.e. the timezone string is not a recognized identifier. The arrow library accepts tz database names ('UTC', 'Europe/Berlin', 'US/Eastern') and offsets; anything else (or a bad offset form) raises internally and is re-raised with this message.

Source

Thrown at changedetectionio/time_handler.py:53

    # Parse the target day of the week
    try:
        target_weekday = Weekday[day_of_week.capitalize()]
    except KeyError:
        raise ValueError(f"Invalid day_of_week: '{day_of_week}'. Must be a valid weekday name.")

    # Parse the start time
    try:
        hour, minute = map(int, time_str.split(':'))
        if not (0 <= hour <= 23 and 0 <= minute <= 59):
            raise ValueError
    except (ValueError, AttributeError):
        raise ValueError(f"Invalid time_str: '{time_str}'. Must be in 'HH:MM' format.")

    # Get the current time in the specified timezone
    try:
        now_tz = arrow.now(timezone_str.strip())
    except Exception as e:
        raise ValueError(f"Invalid timezone_str: '{timezone_str}'. Must be a valid timezone identifier.")

    # Check if the current day matches the target day or overlaps due to duration
    current_weekday = now_tz.weekday()
    # Create start datetime for today in target timezone
    start_datetime_tz = now_tz.replace(hour=hour, minute=minute, second=0, microsecond=0)

    # Handle previous day's overlap
    if target_weekday == (current_weekday - 1) % 7:
        # Calculate start and end times for the overlap from the previous day
        start_datetime_tz = start_datetime_tz.shift(days=-1)
        end_datetime_tz = start_datetime_tz.shift(minutes=duration)
        if start_datetime_tz <= now_tz <= end_datetime_tz:
            return True

    # Handle current day's range
    if target_weekday == current_weekday:
        end_datetime_tz = start_datetime_tz.shift(minutes=duration)
        if start_datetime_tz <= now_tz <= end_datetime_tz:

View on GitHub (pinned to 5d9c7c6da7)

Solutions

1. Use exact IANA tz database names: 'UTC', 'Europe/Berlin', 'America/New_York'
2. Validate with zoneinfo.available_timezones() (Python 3.9+) or a try/except around arrow.now() before saving
3. Offer a dropdown of valid zones in your UI instead of a free-text field
4. Fix existing watch configs in bulk: map common abbreviations to IANA names and re-save

Example fix

# before
am_i_inside_time('monday', '09:00', '1', 'GMT+2')
# after
am_i_inside_time('monday', '09:00', '1', 'Europe/Berlin')

from zoneinfo import ZoneInfo, available_timezones
try:
    ZoneInfo(tz.strip())
    ok = tz.strip() in available_timezones() or True
except Exception:
    ok = False
if not ok:
    raise ValueError('timezone must be an IANA name like Europe/Berlin')

from zoneinfo import ZoneInfo, available_timezones
_TZS = available_timezones()
def is_valid_timezone(s: str) -> bool:
    return s.strip() in _TZS

try:
    inside = am_i_inside_time(day, '09:00', duration, tz)
except ValueError as e:
    return bad_request(str(e))

When it happens

Trigger: Calling am_i_inside_time with timezone_str like 'GMT+2' (wrong syntax), 'est' ambiguity aside — typical failures are 'PST', 'UTC+02', 'berlin', empty string after strip, or None; arrow cannot resolve them to a zone.

Common situations: Watch timezone settings entered as free text; users typing Windows-style zones ('Central Standard Time'); old data using abbreviations like 'CET' or 'EST' that the tz database lookup rejects; trailing quotes from JSON copy-paste.

Related errors

• Invalid day_of_week: '{day_of_week}'. Must be a valid weekda
• Invalid time_str: '{time_str}'. Must be in 'HH:MM' format.
• "{}" is not a valid bool value

AI-assisted analysis of dgtlmoon/changedetection.io@5d9c7c6da7 (2026-08-27). Data as JSON: /api/errors/4547d42cfad0aa67. Report an issue: GitHub.