The HTTPNotAcceptable class is accessible via the paste.httpexceptions module.
'The server could not comply with the request since\r\nit is either malformed or otherwise incorrect.\r\n'
'The resource could not be generated that was acceptable to your browser (content\r\nof type %(HTTP_ACCEPT)s).\r\n%(detail)s'
This exception as a WSGI application
See the source for more information.