Your Sitemap appears to be an HTML page. Please use a supported sitemap format

Hello,

Thank you for contacting Rank Math, and sorry for any inconvenience caused.

That error is caused due to some cache plugin caching your sitemaps.

You only have to submit the sitemap_index.xml in the sitemap section in Search Console.

Can you please follow these steps?
1. Flush the Sitemap cache by following this video screencast:
https://i.rankmath.com/pipRDp

2. Exclude the Sitemap files of the Rank Math plugin in your caching plugin. The cache could be via a plugin or from the server. For plugins or Cloudflare, please follow this article:
https://rankmath.com/kb/exclude-sitemaps-from-caching/

Once done, delete all sitemaps from GSC and submit only the sitemap_index.xml and wait for Google to crawl the sitemap.

That should fix the issue. Please let me know if that does not. We are here to assist.

Hello,

Could you please check the following:
1. Is the sitemap working fine in your browser? You can check that by going domain(.)com/sitemap_index.xml

If the sitemap is working fine, you can try validating it on this link: https://www.xml-sitemaps.com/validate-xml-sitemap.html

If the validation works, please move to the second point.

2. Have you verified the correct version of your website on Google? Please check if you have verified the www (or non-www) and https (or http) version of your website. If there is a mismatch, please fix that.

3. Finally, make sure you have cleared the cache and excluded Google bot from seeing a cached version of your sitemap.

If you have followed these and you are able to view your sitemap without any problem, then Rank Math is outputting your sitemap correctly and the error must be coming from Google. You can try and use a 3rd party sitemap plugin to confirm. Just make sure you have disabled the Sitemap module of Rank Math in WordPress Dashboard > Rank Math > Dashboard when using a 3rd party sitemap plugin.

If the other plugin works, please do let us know.

Thank you.

Hello,

We might need to take a closer look at the settings. Please edit the first post on this ticket and include your WordPress & FTP logins in the designated Sensitive Data section.

It is completely secure and only our support staff has access to that section. If you want, you can use the below plugin to generate a temporary login URL to your website and share that with us instead:

https://wordpress.org/plugins/temporary-login-without-password/

You can use the above plugin in conjunction with the WP Security Audit Log to monitor what changes our staff might make on your website (if any):

https://wordpress.org/plugins/wp-security-audit-log/

We really look forward to helping you.

Hello,

I have enabled the sitemap module in Rank Math and deactivated the other plugin you were using for your sitemap.

Then I cleared the website cache, re-saved permalinks and sitemap settings (without changing anything)

Your sitemap is now working fine and is validated on https://www.xml-sitemaps.com/validate-xml-sitemap.html

Please delete all the sitemaps from Google search console and only submit the sitemap_index.xml and give Google some time to crawl the sitemap.

I hope this helps. Looking forward to helping you.

Hello,

We are super happy that your issue is resolved. If you have any other questions in the future, know that we are here to help you.

If you don’t mind me asking, could you please leave us a review (if you haven’t already) on https://wordpress.org/support/plugin/seo-by-rank-math/reviews/#new-post about your overall experience with Rank Math? We appreciate your time and patience.

If you do have another question in the future, please feel free to create a new forum topic, and it will be our pleasure to assist you again.

Thank you.