Sitemap could not be read error on my website, how to fix this?

Hello,

Thanks for contacting us, and sorry for any inconvenience that might have been caused due to that.

Can you please share your sitemap URL with us? So that we can check that as well.

Meanwhile, please try following the steps below to see if that works for you.

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/

3. Kindly apply the following filter code to your site.

add_filter( 'rank_math/sitemap/enable_caching', '__return_false');

Here’s how you can add filter/hook to your WordPress site:
https://rankmath.com/kb/wordpress-hooks-actions-filters/

Once you’ve done following the above steps, please try re-submitting your sitemap_index.xml on GSC and allow Google a while to crawl your sitemap again.

Let us know how it goes. Looking forward to helping you.

Thank you.