# date_format query parameter returns an error from 2026-10-27

- **Provider:** Meta Graph API
- **Endpoint:** `* /**`
- **Effective:** 2026-10-27
- **Severity:** critical
- **Change:** version-sunset
- **Status:** verified

## What changed

Requests that include the legacy date_format parameter return an error on Graph API v26.0+ since 2026-07-29 and on all supported versions from 2026-10-27. The same change makes pretty and debug ignored and removes ETag/304 Not Modified behaviour.

## What to do

Remove date_format from every Graph API request and parse the default ISO 8601 timestamps in your own code. While you are there, drop any reliance on If-None-Match/304 caching and on pretty or debug output.

## Sources

- Provider notice (2026-07-29): https://developers.facebook.com/docs/graph-api/changelog/version26.0

## Machine-readable

- Advisory: https://github.com/SriVarshini09/shapi-advisories/blob/main/advisories/meta-graph-date-format-param-removed.json
- OSV: https://shapi.dev/osv/meta-graph-date-format-param-removed.json