unsupported_
Registry Context
`unsupported_grant_type` is an OAuth 2.0 token error code indicating that the authorization server does not support the requested authorization grant type.
Technical Summary
RFC 6749 Section 5.2 defines `unsupported_grant_type` as a token error response value. A token error response requires an `error` parameter containing a single ASCII error code. Section 5.2 also restricts the characters allowed in `error`, while Section 11.4.1 applies the same character restriction to registered error names.
When Used
Used in a token error response when the authorization server does not support the requested authorization grant type.
Normative Requirements
Responses
RFC 6749 - Section 5.2
include an `error` parameter containing a single ASCII error code.
error REQUIRED. A single ASCII [USASCII] error code from the following:
RFC 6749 - Section 5.2
include an `error_description` parameter containing human-readable ASCII text that assists the client developer in understanding the error.
error_description OPTIONAL. Human-readable ASCII [USASCII] text providing additional information
RFC 6749 - Section 5.2
include an `error_uri` parameter identifying a human-readable web page with information about the error.
error_uri OPTIONAL. A URI identifying a human-readable web page with information about the error
the `error_description` parameter value
RFC 6749 - Section 5.2
include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
Condition: when the parameter is included
Values for the "error_description" parameter MUST NOT include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
the `error_uri` parameter value
RFC 6749 - Section 5.2
include characters outside the set %x21 / %x23-5B / %x5D-7E.
Condition: when the parameter is included
MUST NOT include characters outside the set %x21 / %x23-5B / %x5D-7E.
RFC 6749 - Section 5.2
conform to the URI-reference syntax.
Condition: when the parameter is included
Values for the "error_uri" parameter MUST conform to the URI-reference syntax
the `error` parameter value
RFC 6749 - Section 5.2
include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
Values for the "error" parameter MUST NOT include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
the registered error name
RFC 6749 - Section 11.4.1
include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
Values for the error name MUST NOT include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
Validation Guidance
Ensure every token error response includes an `error` parameter containing a single ASCII error code.
Ensure `error` values contain only characters from %x20-21 / %x23-5B / %x5D-7E.
Emit `unsupported_grant_type` when the authorization grant type is not supported by the authorization server.
Use HTTP 400 for the token error response unless another status code is specified.
When present, ensure `error_description` contains only characters from %x20-21 / %x23-5B / %x5D-7E.
When present, ensure `error_uri` is a URI-reference and contains only characters from %x21 / %x23-5B / %x5D-7E.
Reject a registered error name containing characters outside %x20-21 / %x23-5B / %x5D-7E.
Reference
Details
- Entry Id
unsupported_grant_ type - Name
unsupported_grant_ type - Usage Location
token endpoint- Protocol Extension
OAuth 2.0 Authorization Framework- Change Controller
IETF- Reference
RFC6749