Issues

• isoparse docstring says an ISO week without a day "defaults to 0", but the day is 1 (Monday) and 0 is rejected

  dateutil/dateutil#1629 · Filter by author Upua opened on Oct 22, 2026

• rrulestr(unfold=True) rejects RFC 5545 HTAB-folded recurrence rules

  dateutil/dateutil#1591 · Filter by author GreedyC opened on Oct 2, 2026

• rrule: BYDAY mixing plain and ordinal weekdays (e.g. MO,1FR) returns the intersection instead of the union

  dateutil/dateutil#1588 · Filter by author fitness-trener opened on Sep 30, 2026
  2

• Feature request: nth ordinal weekday

  dateutil/dateutil#1548 · Filter by author bordenc opened on Aug 10, 2026

• parser.parse( ) also silently truncates fractional seconds beyond 6 digits (via _parsems int(f.ljust(6,"0")[:6]))

  dateutil/dateutil#1546 · Filter by author plotarmordev opened on Aug 8, 2026

• isoparse( ) silently truncates fractional seconds beyond 6 digits (0.1234567 -> 123456us, not rounded 123457us)

  dateutil/dateutil#1545 · Filter by author plotarmordev opened on Aug 8, 2026

• Proposal: speed up parser.parse() (ISO-8601 fast-path + tokenizer hot-path) — gauging appetite before a PR

  dateutil/dateutil#1519 · Filter by author tfoutrein opened on Jun 1, 2026
  1

• parser.parse() silently accepts invalid timezone offsets (minutes >= 60, hours >= 24); inconsistent with isoparse()

  dateutil/dateutil#1508 · Filter by author zhangjiashuo-cs opened on May 24, 2026

• UTC-4 parsed to +04:00

  dateutil/dateutil#1478 · Filter by author c-leber opened on Apr 6, 2026

• Issue with Python 3.15 alpha 7 and build of docs

  bugbuilddocumentation
  dateutil/dateutil#1472 · Filter by author frenzymadness opened on Mar 23, 2026
  2

• FREQ=YEARLY with BYMONTHDAY but no BYMONTH expands to every month instead of DTSTART month (RFC 5545 non-compliance)

  dateutil/dateutil#1452 · Filter by author laydros opened on Jan 31, 2026

• dayfirst implementation bug

  dateutil/dateutil#1448 · Filter by author bernd-wechner opened on Dec 23, 2025

• parser.parse fails on "year:month:day h:m:s"

  dateutil/dateutil#1447 · Filter by author lovely-fafa opened on Dec 5, 2025

• Parser cannot handle common datetime format used in image metadata

  dateutil/dateutil#1446 · Filter by author fizbin opened on Nov 28, 2025

• default parser fails to parse 9-digit time string as HHMMSSmmm format

  dateutil/dateutil#1442 · Filter by author HydrogenDeuterium opened on Oct 16, 2025
  1

• Infinite loop in rrule.py

  dateutil/dateutil#1441 · Filter by author jmbarbier opened on Oct 2, 2025

• Typeerror while trying to interate over rrule

  dateutil/dateutil#1438 · Filter by author owenhollands opened on Sep 7, 2025

• OverflowError: timestamp out of range for platform time_t

  dateutil/dateutil#1436 · Filter by author pbiering opened on Aug 23, 2025
  3

• TypeError in tzstr when parsing "UTC" or "GMT" without offset

  dateutil/dateutil#1432 · Filter by author shukuchicoding opened on Jul 4, 2025

• If a mock object reaches parse() during a unit test, unbounded memory allocation occurs

  dateutil/dateutil#1428 · Filter by author pete-kirkham opened on May 23, 2025
  1

• rrule generated creates datetimes with non-existent local time (i.e., not respecting DST gaps)

  dateutil/dateutil#1425 · Filter by author BurntSushi opened on Apr 8, 2025
  2

• "5pm" with a default date is not considered "5:00pm"

  dateutil/dateutil#1421 · Filter by author dvklopfenstein opened on Mar 8, 2025
  2

• handle and parse date ranges

  dateutil/dateutil#1414 · Filter by author lipeaaraujo opened on Feb 8, 2025

• timezone definition inconsistencies in the past

  dateutil/dateutil#1413 · Filter by author niccokunzmann opened on Feb 6, 2025

• Fuzzy parser returns wrong year

  dateutil/dateutil#1410 · Filter by author jaagut opened on Jan 23, 2025
  2