XML sitemap resolving as HTML file

Question

I'm running a few Wordpress installs on Azure Websites, and when I go to the sitemaps that were generated by the Yoast SEO plugin they look like static html, (usually the browser will view it as an XML document)

I've added 

<mimeMap fileExtension=".xml" mimeType="text/xml" />

Under <staticContent> but this doesn't seem to resolve the problem. I have scanned the sitemap with a validator and it says it is invalid (Incorrect http header content-type). I fear this is could effect sites on Bing and Google.

I see there is a handler mappings. I don't know if that would resolve the issue or not. Can anyone assist? I am having problems getting a site crawled, and I think this may be the problem, but I don't know how to solve it.

Answer 1

The solution for the error you've described has been documented in this Yoast KB article - Sitemap Error: Unsupported format HTML. If despite following that document the issue persists then I suggest reaching out to Yoast technical support since the error is more to do with sitemaps generated by the Yoast SEO plugin than with Azure App Service platform.

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Answer 2

Thanks! I tracked it down to it being the caching plugin I was using, WP Super Cache; for those in the future, add what I have to the cache settings under the string list not to cache under advanced options:

sitemap_index.xml
.*-sitemap.xml