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Messaging and Platform API requests accept a date version in the Polymorfa-Version header:
The current and minimum version is 2026-09-22. When the header is omitted, the API uses the current version. The resolved value is echoed in the response as Polymorfa-Version. This revision uses whatsapp_ids for native message provider references in responses and events. Read linked_devices, official_api, or both from that object; use the stable Polymorfa id for message actions. Native message responses and webhooks also carry the earlier whatsapp_id field during the migration window. New integrations should read whatsapp_ids; existing integrations can migrate without losing their provider reference.

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Current request

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Versions below the minimum

A version earlier than the configured minimum returns 400 before the route handler runs. This includes the retired 2026-03-20; remove the header or send 2026-09-22. The response includes:
The Link header points to version guidance. The docs field links to the error’s recovery steps. Malformed dates, including impossible calendar dates, return 400 with error.code: invalid_parameter and error.param: Polymorfa-Version.

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Versions newer than the current contract

A date later than 2026-09-22 returns 400 with error.code: invalid_parameter and error.param: Polymorfa-Version before the request runs. Remove the header or send 2026-09-22.

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Older supported versions

When a configured version is older than the current version but still meets the minimum, the request continues and can include:
  • Sunset when a sunset date is configured;
  • Polymorfa-Deprecation-Warning; and
  • a Link with rel="sunset".

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Graph API versions

Graph requires a Meta-style version segment in the URL:
Polymorfa forwards the URL version for operations it sends to Meta. Changing it does not change the behavior of Polymorfa’s media, phone-number, or business-profile methods, or Linked Device operations. Polymorfa-Version does not apply to Graph requests, for either connection type.

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API paths