I am getting a 404 error while trying to setup sitemap.

Hello, we apologize for the inconvenience you’re facing with setting up the sitemap. We understand the frustration this may cause. Have you tried validating your sitemap using the Validate XML Sitemap tool as mentioned in our knowledgebase article on troubleshooting the “Couldn’t Fetch” Error in Google Search Console? If not, please give it a try and let us know if it resolves the issue. If you’ve already tried this, please provide more details about the steps you’ve taken so far, and we’ll be happy to assist you further.

Sources:
Why the Sitemap_Index.xml is Throwing a 404 Error » Rank Math
How to Configure Sitemaps in Rank Math – Best Settings and Tips
Troubleshooting the “Couldn’t Fetch” Error in Google Search Console » Rank Math
Indexed, Not Submitted in Sitemap – Google Search Console » Rank Math
Using Video Sitemaps in Rank Math

Hello,

Thank you for your patience.

We’ve checked your site, and it seems that you don’t have any pages or posts published yet.

When you already have published a page/post, then you can visit your sitemap. If it’s still returning 404, then follow these steps to flush your sitemap cache:

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. Disable the transient cache for the sitemap by applying this filter. This will make sure that your XML sitemap always reflects the latest changes on your site:

/** 
 * Filter if XML sitemap transient cache is enabled.
 *
 * @param boolean $unsigned Enable cache or not, defaults to true
 */
add_filter( 'rank_math/sitemap/enable_caching', '__return_false');

Once done, remove all your submitted sitemaps and resubmit your main sitemap only /sitemap_index.xml

Then give Google some time to recrawl your site.

Lastly, you shouldn’t inspect your sitemap URL in your Google Search Console account as it is set to noindex by default to prevent it from showing on the search results page.

Here’s a guide on how to properly submit your sitemap:
https://rankmath.com/kb/submit-sitemap-to-google/

Hope that helps.

Hello,

You’re welcome.

We’re glad that we have addressed your concern. 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.