pandas-dev/pandas · error · ValueError

Offset {offset} did not decrement date

Error message

Offset {offset} did not decrement date

What it means

Mirror of 295 for a descending range: applying offset._apply(cur) does not move the date backward (next_date >= cur), so the loop cannot terminate. ValueError naming the offset. Reached via date_range with a negative direction or a backwards iteration.

Source

Thrown at pandas/core/arrays/datetimes.py:3290

            next_date = offset._apply(cur)
            next_date = next_date.as_unit(unit)
            if next_date <= cur:
                raise ValueError(f"Offset {offset} did not increment date")
            cur = next_date
    else:
        while cur >= end:
            yield cur

            if cur == end:
                # GH#24252 avoid overflows by not performing the addition
                # in offset.apply unless we have to
                break

            # faster than cur + offset
            next_date = offset._apply(cur)
            next_date = next_date.as_unit(unit)
            if next_date >= cur:
                raise ValueError(f"Offset {offset} did not decrement date")
            cur = next_date

View on GitHub (pinned to 71959b8cb9)

Solutions

1. Ensure the offset strictly decrements dates (offset.n < 0 or apply yields earlier timestamps).
2. Use a negative freq string ('-1D') or reverse a forward range with [::-1].
3. Validate custom DateOffset.apply is strictly monotonic in the expected direction.

Example fix

# before
pd.date_range('2020-01-10', '2020-01-01', freq=pd.DateOffset(days=0))
# after
pd.date_range('2020-01-10', '2020-01-01', freq='-1D')

def make_range_desc(start, end, offset):
    if getattr(offset, 'n', 0) >= 0:
        raise ValueError(f'offset {offset!r} must be strictly negative for backward range')
    return pd.date_range(start, end, freq=offset)

When it happens

Trigger: Generating a reverse date_range with an offset that is non-negative or zero; a custom offset whose apply does not strictly decrement; freq with n >= 0 used in a backward context.

Common situations: Sign error when building an offset for descending ranges; custom offset logic that adds instead of subtracts.

Related errors

• Offset {offset} did not increment date
• overflow in timedelta operation
• Cannot compare tz-naive and tz-aware datetime-like objects.
• Cannot compare tz-naive and tz-aware datetime-like objects
• Cannot convert tz-naive timestamps, use tz_localize to local

AI-assisted analysis of pandas-dev/pandas@71959b8cb9 (2026-08-07). Data as JSON: /api/errors/cf130195fc75d099. Report an issue: GitHub.