I use the Admin Tools's option to convert all links to HTTPS, and it is amazing because I don't waste to many time to do it manually but it change also the namespace identifier in my xml sitemap...
So into the sitemap.xml the line:
xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
became:
xmlns="https://www.sitemaps.org/schemas/sitemap/0.9"
and Google Search Console return this error:
"Your Sitemap or Sitemap index file declares the namespace incorrectly"
How can I fix it, please? Thanks
I also wrote in Google webmaster help central forum here:
https://productforums.google.com/forum/#!topic/webmasters/8f273s3t0oM;context-place=forum/webmasters