[kontrabass]

Originally Posted by Cloudrunner

Just a clarification the filename *should* be sitemap_index.xml.gz

The reason is that if you set your URL amount to split at say 20,000 links (default option) then you will have up to three files, sitemap_1.xml.gz, sitemap_2.xml.gz and sitemap_3.xml.gz if you have more than 20,000 URLs in your sitemap up to a total of the 50,000 URLs allowed by Google.

The sitemap_index.xml.gz tells google where to find the rest of the files after the split has occured. As well, even if you only have one file, it will still point google to the correct file location.

It also appears that if no modifications are made except to the .htaccess as you have instructed, the sitemap_index.xml.gz file will point to the child maps incorrectly (uses /forum/sitemap_1.xml.gz instead of siteroot/sitemap_1.xml.gz)