Provide custom unfurl behavior for user-posted URLs.

Required Params

• channel - Channel ID of the message. ex: C1234567890
• ts - Timestamp of the message to add unfurl behavior to. ex: 1405894322.002768
• unfurls - URL-encoded JSON map with keys set to URLs featured in the the message, pointing to their unfurl blocks or message attachments.

Optional Params

• user_auth_message - Provide a simply-formatted string to send as an ephemeral message to the user as invitation to authenticate further and enable full unfurling behavior.
• user_auth_required - Set to true or 1 to indicate the user must install your Slack app to trigger unfurls for this domain. ex: true
• user_auth_url - Send users to this custom URL where they will complete authentication in your app to fully trigger unfurling. Value should be properly URL-encoded.. ex: https://example.com/onboarding?user_id=xxx

Errors the API can return:

• method_deprecated - The method has been deprecated.
• cannot_find_channel - The specified channel could not be located for this token.
• cannot_unfurl_message - The URL cannot be unfurled because the URL provided does not appear in the message.
• invalid_charset - The method was called via a POST request, but the charset specified in the Content-Type header was invalid. Valid charset names are: utf-8 iso-8859-1.
• request_timeout - The method was called via a POST request, but the POST data was either missing or truncated.
• missing_post_type - The method was called via a POST request and included a data payload, but the request did not include a Content-Type header.
• service_unavailable - The service is temporarily unavailable
• ratelimited - The request has been ratelimited. Refer to the Retry-After header for when to retry the request.
• no_permission - The workspace token used in this request does not have the permissions necessary to complete the request. Make sure your app is a member of the conversation it's attempting to post a message to.
• two_factor_setup_required - Two factor setup is required.
• invalid_arguments - The method was either called with invalid arguments or some detail about the arguments passed are invalid, which is more likely when using complex arguments like blocks or attachments.
• invalid_auth - Some aspect of authentication cannot be validated. Either the provided token is invalid or the request originates from an IP address disallowed from making the request.
• not_allowed_token_type - The token type used in this request is not allowed.
• org_login_required - The workspace is undergoing an enterprise migration and will not be available until migration is complete.
• cannot_prompt - The current user has already interacted with and dismissed a prompt for this application.
• invalid_unfurls_format - The unfurls parameter cannot be JSON-decoded into a map of URLs to attachments.
• missing_ts - The request is missing the ts parameter
• enterprise_is_restricted - The method cannot be called from an Enterprise.
• cannot_parse_attachment - The provided unfurls argument could not be parsed or understood.
• accesslimited - Access to this method is limited on the current network
• invalid_form_data - The method was called via a POST request with Content-Type application/x-www-form-urlencoded or multipart/form-data, but the form data was either missing or syntactically invalid.
• cannot_unfurl_url - The URL cannot be unfurled. This error may be returned if you haven't acknowledged a link_shared event tied to the same URL. It is also returned when the domain appears in a workspace's administrative blacklists.
• invalid_array_arg - The method was passed an array as an argument. Please only input valid strings.
• deprecated_endpoint - The endpoint has been deprecated.
• token_revoked - Authentication token is for a deleted user or workspace or the app has been removed.
• cannot_find_service - A record of your app being allowed to unfurl for this workspace could not be found.
• invalid_post_type - The method was called via a POST request, but the specified Content-Type was invalid. Valid types are: application/json application/x-www-form-urlencoded multipart/form-data text/plain.
• missing_channel - The request is missing the channel parameter
• invalid_arg_name - The method was passed an argument whose name falls outside the bounds of accepted or expected values. This includes very long names and names with non-alphanumeric characters other than _. If you get this error, it is typically an indication that you have made a very malformed API call.
• is_bot - This method cannot be called by a bot user.
• team_added_to_org - The workspace associated with your request is currently undergoing migration to an Enterprise Organization. Web API and other platform operations will be intermittently unavailable until the transition is complete.
• missing_unfurls - The request is missing the unfurls parameter.
• not_authed - No authentication token provided.
• fatal_error - The server could not complete your operation(s) without encountering a catastrophic error. It's possible some aspect of the operation succeeded before the error was raised.
• cannot_find_message - The ts value in the request does not match a message.
• account_inactive - Authentication token is for a deleted user or workspace.
• internal_error - The server could not complete your operation(s) without encountering an error, likely due to a transient issue on our end. It's possible some aspect of the operation succeeded before the error was raised.
• ekm_access_denied - Administrators have suspended the ability to post a message.
• missing_scope - The token used is not granted the specific scope permissions required to complete this request.