tzdata

# Changelog for Tzdata

## [Unreleased]

## [1.2.2] - 2026-09-25

### Fixed

- Fix a pattern match bug in `latest_file_size/1` that caused the HEAD
  request used to check the latest tzdata file size to always fail,
  silently falling back to a GET request instead. (Matt Wynne)
- Fix a compile warning about an unused `require Logger` when Hackney
  isn't available. (Michel Boaventura)

## [1.2.1] - 2026-09-15

### Fixed

- Fix a compile error on Erlang/OTP 28+ caused by regexes compiled into
  module attributes in the leap seconds parser. (Thijs Klaver)

## [1.2.0] - 2026-09-13

### Added

- Parse the IANA `factory` source file, adding the placeholder `Factory`
  zone (previously omitted) to the zone list.

### Changed

- Now requires Elixir 1.12 or greater instead of 1.9 or greater.
- Hackney is no longer a mandatory dependency. When `:http_client` isn't
  configured explicitly, Tzdata now automatically picks the best available
  HTTP client: the built-in `:httpc`, verifying certificates via
  `:public_key.cacerts_get/0` (the OS-trusted CA bundle), when that's
  usable (Erlang/OTP 25+); otherwise Hackney, if it's present as a
  dependency; otherwise `:httpc` is still used but automatic updates are
  skipped with a warning rather than downloading without verification. See
  the README's "HTTP client and security" section for details.
- Debug log messages for downloading new data now include the name of the
  HTTP client in use (e.g. `httpc` or `hackney`).
- tzdata release version shipped with this library is now 2026d instead of 2026c.

### Deprecated

- Hackney support is deprecated and will be removed in a future release.
  Using `Tzdata.HTTPClient.Hackney` now logs a warning. It is strongly
  recommended to use Erlang/OTP 25 or higher, where the built-in `:httpc`
  client is used by default and no HTTP client dependency is needed.

### Fixed

- Fix incorrect or spurious historical time zone periods (wrong or blank abbreviations before a zone's earliest rule, and redundant zero-effect periods at zone-line boundaries) affecting many zones, including America/Regina, America/Chicago, America/Edmonton, America/Inuvik, Antarctica/Troll, America/Chihuahua, America/Argentina/Buenos_Aires, Europe/Dublin, Europe/Vienna, Europe/Istanbul, and most former Soviet zones.

## [1.1.5] - 2026-09-06

### Fixed

- Fix Africa/Casablanca and Africa/El_Aaiun switching to permanent UTC six
  months early in tzdata 2026c, and similar errors in some historical
  transitions, caused by a zone line whose rules end before the line does.

### Changed

- tzdata release version shipped with this library is now 2026c instead of 2026b.
- Now supports version 4.x of hackney as well as 1.x

## [1.1.4] - 2026-06-22

### Fixed

- Fix :calendar crash on OTP 29 for IANA "24:00" transition times (Patrick Olsen)

### Changed

- tzdata release version shipped with this library is now 2026b instead of 2025a.

## [1.1.3] - 2025-03-05

### Fixed

- Fix Elixir compiler warnings for decreasing ranges without explicit steps (Christoph Grothaus)
- Fix various Elixir compiler warnings (Thomas Cioppettini)

### Changed

- Now requires Elixir 1.9 or greater instead of 1.8 or greater.
- tzdata release version shipped with this library is now 2025a instead of 2024b.

## [1.1.2] - 2024-09-09

### Fixed

- Can handle months being spelled out instead of abbreveated to 3 letters as happened in one place in 2024b. (Moxley Stratton)

### Changed

- tzdata release version shipped with this library is now 2024b instead of 2021e.

## [1.1.1] - 2021-10-31

### Fixed

- Fix period overlaps for certain zones (Jarrod Moldrich)

### Changed

- tzdata release version shipped with this library is now 2021e instead of 2020e.
- Call :rand instead of :random for avoiding warnings

## [1.1.0] - 2020-12-26

### Fixed

- Fixed Elixir 1.11 compilation warnings. (Ho-Yon Mak)

### Changed

- Increased hackney dependency version requirement to ~> 1.17
- tzdata release version shipped with this library is now 2020e instead of 2020d.

## [1.0.5] - 2020-11-27

### Fixed

- Fix issues with Tzdata.TimeZoneDatabase during gaps (Benjamin Milde)

### Changed

- tzdata release version shipped with this library is now 2020d instead of 2019c.

## [1.0.4] - 2020-10-07

### Fixed

- Fix warning in Elixir 1.11 (Thanabodee Charoenpiriyakij)

## [1.0.3] - 2019-12-19

### Changed

- tzdata release version shipped with this library is now 2019c instead of 2019a.

### Fixed

- Hackney was not set as an "application" in non-dev environments in 1.0.2 and could cause errors in updating.

## [1.0.2] - 2019-10-17

### Fixed

- Avoid creating atoms for non-existing time zone names.

## [1.0.1] - 2019-07-01

### Fixed

- Fixed: could not process 2019b release. Error related to `first_matching_weekday_in_month(1932, 4, 7, [])`.

## [1.0.0] - 2019-04-23

### Changed

- Elixir version requirement increased to Elixir 1.8+
- ETS table normalization for performance improvements over 0.5.x releases
- .ets release files now have contents with a different structure
- Because of the different structre the .ets files now have a different file ending. E.g.: 2019a.v2.ets

### Added

- Tzdata.TimeZoneDatabase module that implements the Calendar.TimeZoneDatabase behaviour.

Changelog for v0.5.x releases can be found [in the pre_1-8 branch](https://github.com/lau/tzdata/blob/pre_1-8/CHANGELOG.md).