> ## Documentation Index > Fetch the complete documentation index at: https://www.text.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Authentication errors > OAuth error codes returned by the Text authorization server, their meanings, and possible causes. All authorization errors redirect to `https://accounts.livechat.com/ooops`, while authentication errors redirect to `https://accounts.livechat.com/`. Error codes are returned in the query string as the `oauth_exception` parameter (for authorization errors) or `identity_exception` parameter (for authentication errors). An additional `exception_details` parameter may be included with more specific information. ## Authorization errors ### `invalid_request` The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. Possible reasons: * wrong HTTP method * invalid HTTP body encoding ### `unauthorized_client` The client is not authorized to request a token using this method. Possible reasons: * missing client ID * client ID not found * refresh token not found * invalid client secret * invalid redirect URI ### `access_denied` The resource owner or authorization server denied the request. Possible reasons: * the requested scopes include a scope that wasn't originally granted by the resource owner Not helpful? See [`access_denied`](#access_denied-1) in Authentication errors. ### `unsupported_response_type` The authorization server does not support obtaining a token using this method. Possible reasons: * response type is not `code` or `token` ### `invalid_scope` The requested scope is invalid, insufficient, unknown, or malformed. Possible reasons: * scope not found * scope name not found * an app requires `administrator` scopes, but an `agent` user was logged in ### `server_error` The authorization server encountered an unexpected condition that prevented it from fulfilling the request. Possible reasons: * server down * server storage down Not helpful? See [`server_error`](#server_error-1) in Authentication errors. ### `temporarily_unavailable` The authorization server is currently unable to handle the request due to a temporary overload or maintenance. Currently not used. ### `unsupported_grant_type` The authorization grant type is not supported by the authorization server. * using a disabled authorization grant type, for example client credentials grant; read more ### `invalid_grant` The provided authorization grant or refresh token is invalid, expired, revoked, does not match the redirection URI, or was issued to another client. Possible reasons: * refresh token expired * access token expired ### `invalid_client` Client authentication failed. Possible reasons: * using a refresh token with the wrong client ID ### `missing_grant` The client is missing granted rights. Possible reasons: * grants were rejected * grants were never given * client changed required grants ### Exception details `client_id_not_found` — wrong client ID; the client ID does not exist `redirect_uri_not_set` — client misconfiguration; the client has not set a redirect URI `invalid_redirect_uri` — redirect URI is not one of the client's allowed redirects `too_many_redirects` — the server detected a redirect loop; the client is redirecting too many times ## Authentication errors ### `invalid_request` The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. Not helpful? See [`invalid_request`](#invalid_request) in Authorization errors. ### `unauthorized` The request is valid, but the identity data is wrong or the identity does not exist. If the identity ID is known, it is added to the query string as `entity_id`. ### `server_error` The server encountered an unexpected condition that prevented it from determining the identity. Not helpful? See [`server_error`](#server_error) in Authorization errors. ### `access_denied` The identity is known, but access is denied for business reasons — for example, the identity is banned or has the wrong account version. Not helpful? See [`access_denied`](#access_denied) in Authorization errors. ### `identity_lost` The identity was removed due to logout, password reset, or remote logout. ### `credentials_login_disabled` The identity has disabled the credentials login strategy. The identity should be verified with another strategy such as Google OAuth or SAML.