Would probably be no luxury to mention that you are talking about an error that seems to pop up in Google Webmaster Console. However: The status there about the sitemap has been broken for years. It does not to seem have any negative effect and Google does not seem to bother to show a correct status there. Often enough it is claiming that there would be no sitemap, even if you pointed it to the correct location. It does index anyway, so the warning seems kind of pointless and wrong as well.
