Please be sure that you are submitting your sitemap as a URL rather than trying to upload a static file.
If that does not solve the problem, then please tell me what your website URL is.
~ Kim ~
On Behalf of Team Yoast
I Kim,
I think that I have submitted as a URL.
The url is http://www.chicnailspiacenza.com
At this moment the total pages is 1.221.
You can reduce the number of pages and posts listed in a sitemap in SEO > XML Sitemaps.
Scroll down the page. There is a field to reduce that number. Try 500 instead of the default 1000.
But if I reduce this value all the pages will be indexed?
Yes, if you reduce the number, they will still be indexed. The sitemap merely splits them into multiple sitemaps. 🙂
Example: post-sitemap.xml, post-sitemap2.xml, etc
I tried to set at 500, but there is only one sitemap: http://awesomescreenshot.com/07a5b8ot69
I tried also to deactivate all plugins, but it’s the same.
Hi chicnailspc
In your screenshot: http://www.awesomescreenshot.com/02d5b8nnb0
Can you translate into English, for me, what that “Problem” and “Description” says?
Additionally, when viewing your sitemap http://chicnailspiacenza.com/sitemap_index.xml I see that it is now split up better. It was probably a caching problem causing it not to update earlier. Please re-try submitting that url ^^ to Google Search Console.
If you need additional personalized assistance to help you get this solved we also offer Premium support which you can learn more about at http://kb.yoast.com/article/160-support
~ Kim ~
Support at Yoast