Shopify is a very practical SaaS solution, but like any software, there can sometimes be small bugs.
In this case, on several stores that we have been able to develop, it may happen that the sitemap of the pages is not recognized by Google.
The sitemap file is very important for the SEO of a Shopify online store. It is therefore an element that should not be overlooked. We have already discussed it here if you want all the explanations: Shopify xml sitemap
But what's wrong with Shopify's sitemap?
If you tried to load the Shopify sitemap in your Webmaster Tool console, you may have encountered the following issue:
“Unable to retrieve sitemap”

This error mainly occurs on the Shopify sitemap pages, but it doesn't seem to affect all stores. If you're also experiencing a problem like "Unable to retrieve sitemap," we have the solution!
How to fix “Unable to retrieve sitemap” from Shopify?
The only solution we have found so far is to add a second sitemap in Google's Webmaster Tool Console with a working sitemap.
It is often accessible by removing the “_1” from the sitemap URL of the pages.
For example, if your “official” Shopify sitemap for your pages is “ https://pikka.fr/sitemap_pages_1.xml ” you can also access it via the url https://pikka.fr/sitemap.xml to see what the real url of your Sitemap is because it is 100% functional.
Simply add the URL in the space provided to add a new sitemap and click “Submit”.

You can indeed have multiple sitemaps for the same Shopify site, no worries for your SEO.
After a few seconds, Google Webmaster Tool should tell you the number of URLs in your pages and a message “Operation completed”.
And there you have it, you have just fixed the main problem with SHOpify and the Sitemap file.
Why isn't this problem fixed by Shopify?
We haven't received an official response from Shopify, but the issue has been noted in forums. We don't even know if this is a common issue for all stores. Perhaps because the solution is relatively easy, Shopify hasn't put this issue at the top of its to-do list.
In short, we hope that the problem will be fixed in the future, but until then, you will finally have a solution to fix your sitemap feed issues in your Google Webmaster Console.