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Messaging API requests can send a date version in the Titan-Version header:
The current and minimum configured version is 2026-03-20. When the header is omitted, the API uses the current version. The resolved value is echoed in the response as Titan-Version.

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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. The response includes:
Follow the response’s docs URL rather than constructing a migration URL.

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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;
  • Titan-Deprecation-Warning; and
  • a Link with rel="sunset".
No older version is supported because the current and minimum dates are the same.

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Meta-compatible versioning

Meta-compatible Messaging API operations use the vNN.0 segment in their path. Keep native and Meta-compatible version selection separate; Titan-Version does not replace the path version.