ServiceNow API permissions issue

issue when attempting to update/create a sys_user record via API call into the instance:

: [ InsufficientPermissionException ] [ Possible suggestions ] Furnish appropriate permissions to the user. [ Error details ] Insufficient privileges detected. Status: 403 , Output: External User Not Authorized, Detail: , Status: failure

Resolution:

It seems, either during the zboot, or the clone, the sandbox instance lost the roles that are enabled when the high security plugin is installed (snc_internal and snc_external). I copied the roles from our dev instance over to the sandbox instance and then added all users to the snc_internal role. This solved the problem with the app and update set pickers, it might resolve this API issue also as I believe that snc_internal is required for the REST API’s.