Cannot update a query once a slice has been taken.

Raise code

def update(self, **kwargs):
        """
        Update all elements in the current QuerySet, setting all the given
        fields to the appropriate values.
        """
        self._not_support_combined_queries('update')
        if self.query.is_sliced:
            raise TypeError('Cannot update a query once a slice has been taken.')
        self._for_write = True
        query = self.query.chain(sql.UpdateQuery)
        query.add_update_values(kwargs)
        # Clear any annotations so that they won't be present in subqueries.
        query.annotations = {}
        with transaction.mark_for_rollback_on_error(using=self.db):
            rows = query.get_compiler(self.db).execute_sql(CURSOR)