3.4.2.5.6 Sending 403 Forbidden response (Action: Block clients with upgrade)

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This section follows the behavior described in product behavior note <172>.

If the server determines that it does not support the version specified in the User-Agent header, it SHOULD respond with a 403 Forbidden error. If the action configured for the version of the UAC is to block and respond with an upgrade notification hinting to the client to upgrade from an upgrade service, the server SHOULD include a Warning header, as specified in [RFC3261] section 7.3.1. The value of the Warning header MUST be constructed as follows:

  • Warn-code is set to the value 314.

  • Warn-agent is set to the value "lcs.microsoft.com".

  • Warn-text is set to the quoted string "Check Microsoft Update for the newest version."

The following is an example of this Warning header.

 Warning: 314 lcs.microsoft.com "Check Microsoft Update for the newest version."