Applies to: Listings or receipts that contain a nonexistent day within a named month.
The useful distinctions
- A Gregorian date requires a valid day for its month and year.
- November has no 31st day.
- Offset arithmetic starts from a valid timestamp rather than correcting an organiser’s calendar intent.
Do not make a source error look precise
A conversion tool may reject an impossible date, or another system may normalise it into a later day. Neither behaviour tells the viewer what the organiser intended. A polished converted timestamp can hide this uncertainty and make a fabricated occurrence appear authoritative. Check that the original year, month and day form a valid calendar date before comparing locations, calculating a duration or deciding that a guide is one day out.
Keep correction and conversion separate
Ask whether the source intended the preceding valid day, the following month or a different month altogether. Preserve the original text and the confirmed correction in the support record. Once the date is corrected, a normal timezone conversion may still cross midnight; that is a separate transformation. Recording both stages lets another reader see which change came from the organiser and which came from the viewer’s clock context.
Hypothetical worked example
A fictional programme notice gives 31 November 2026 at 22:00 UTC. The viewer does not automatically turn it into 1 December or call it a timezone error. Support confirms that 30 November was intended. The viewer then converts that corrected timestamp for their location and records the confirmation date. A later reader can distinguish the original calendar mistake from any legitimate next-day local reading of the corrected event.
A focused way to proceed
- Copy the invalid date exactly in a private source note.
- Request the intended calendar date.
- Convert only the corrected occurrence and retain the correction history.
When to stop or ask for help
Ask the listing owner to supply a valid original date; avoid publishing a guessed replacement occurrence.