# idna v3.19

- Product: idna (https://whatsnew.fyi/product/idna)
- Vendor: idna
- Date: 2026-08-18
- Version: v3.19
- Original notes: https://github.com/kjd/idna/releases/tag/v3.19
- Permalink: https://whatsnew.fyi/product/idna/releases/v3.19

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **changed** — Restore the std3_rules option, which had no effect since changes to UTS #46 processing in Unicode 16
- **changed** — uts46_remap() now defaults to enabling STD3 rules, causing input containing non-LDH ASCII characters to be rejected
- **changed** — Performance improvements to UTS #46 mapping, particularly for ASCII-only domains
- **added** — Test on free-threaded CPython with the GIL disabled and document thread safety
- **added** — Expose the Unicode version of the generated tables as idna.unicode_version and show it in idna --version
- **added** — Add code, text, codepoint and position attributes to IDNAError so that the failed rule and the offending character can be identified
- **changed** — The deprecated transitional argument to encode() and uts46_remap() is now completely ignored, and gives a deprecation warning for the latter
- **fixed** — Reject A-labels that are not the canonical Punycode encoding of their U-label
- **fixed** — Fix CONTEXTJ violations raising IDNAError instead of InvalidCodepointContext
- **fixed** — Consistently raise IDNAError for empty labels and non-ASCII bytes passed to label helper functions and the incremental codec

- Restore the `std3_rules` option, which had no effect since changes
  to UTS #46 processing in Unicode 16. Note that `uts46_remap()`
  defaults to enabling STD3 rules, so direct callers will see input
  containing non-LDH ASCII characters rejected again.
- Performance improvements to UTS #46 mapping, particularly for
  ASCII-only domains.
- Test on free-threaded CPython with the GIL disabled and document
  thread safety.
- Expose the Unicode version of the generated tables as
  `idna.unicode_version`, and show it in `idna --version`.
- Add `code`, `text`, `codepoint` and `position` attributes to
  `IDNAError` so that the failed rule and the offending character can
  be identified without parsing the exception message.
- The deprecated `transitional` argument to `encode()` and
  `uts46_remap()` is now completely ignored, and gives a deprecation warning
  for the latter.
- Reject A-labels that are not the canonical Punycode encoding of
  their U-label.
- Fix CONTEXTJ violations raising `IDNAError` instead of
  `InvalidCodepointContext`.
- Consistently raise `IDNAError` for empty labels and non-ASCII bytes
  passed to label helper functions and the incremental codec.
- Add property-based tests, extended fuzzing targets, coverage
  measurement, and CI checks that the data tables match the generator
  output.
- Various code quality and tooling improvements.

Thanks to stefan6419846, LouieLuNZ, and Salvatore Corvaglia for
contributions to this release.