If the access code request fails for any reason, or if one of the request parameters is invalid, then an error occurs.
The authorization server may return a response containing information about the error. This might be in JSON format (or XML or other) and may have the following format:
{ "error":"invalid_request", "error_description":"Username parameter missing"}Possible Error Values
The error parameter can contain a number of values that describe the nature of the problem that occurred. These values and descriptions are as follows:
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invalid_request: The request is missing a parameter or value, a parameter is included multiple times, or a parameter has a malformed name.
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invalid_client: The authentication of the client fails. This can happen if authentication parameters are missing (for example, the client identifier and secret) or if the client tries to authenticate using an unsupported method.
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invalid_grant: The grant specified is invalid, expired, or revoked, or supplied to another client. For example, some services don't allow a new access token to be requested until the currently issued token expires.
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unauthorized_client: The client was authenticated by the authorization server, but has no authorization to use the requested grant.
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unsupported_grant_type: The grant that was requested isn’t supported by the authorization server.
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server_error: The Authorization Server encountered an unexpected condition that prevented it from fulfilling the request.
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temporarily_unavailable: The authorization server is currently unable to handle the request because of a temporary overloading or maintenance of the server.
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invalid_scope: The scope specified in the request isn’t valid, is unknown, or is malformed. If this occurs, then read the developer documentation associated with the service provider to see which scopes are available and which can be used.
Error Description
Only the error parameter is mandatory. But the optional error_description parameter may contain a short message explaining the error, for example, indicating a missing user name.
