General HTTP error: 404 not found – in Google Webmaster Tools

[Do not post in all caps – topic modified]

I spent 3 days researching the issue and trying every possible solution. I love the plugin, but the 404 issue seems to be insurmountable.

The error message that I receive:
We encountered an error while trying to access your Sitemap.
General HTTP error: 404 not found
Sitemap: skylark-studio.com/portfolios-sitemap.xml
HTTP Error: 404

Out of 4 sitemaps only portfolios-sitemap.xml gives this error.

—

WordPress version: 3.5.1
WordPress SEO version: 1.4.10

I did this:

Troubleshooting steps.

1. All plugins were disabled. The only active plugin was SEO Woredpress

2. No caching solution installed – so nothing can interfere.

3. Disabling/reanabling plugin and resubmitting the sitemap in google webmaster doesn’t help.

4. Disabling/reanabling sitemap functionality in pluign and resubmitting the sitemap in google webmaster doesn’t help.

5. Adding fix to .htacces doesn’t help
Here is how my .htaccess looks:

# WordPress SEO - XML Sitemap Rewrite Fix
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^sitemap_index\.xml$ /index.php?sitemap=1 [L]
RewriteRule ^([^/]+?)-sitemap([0-9]+)?\.xml$ /index.php?sitemap=$1&sitemap_n=$2 [L]
</IfModule>
# END WordPress SEO - XML Sitemap Rewrite Fix

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

6. Adding lines of code to /wp-content/plugins/wordpress-seo/inc/class-sitemaps.php doesn’t help.
Here is how my class-sitemaps.php looks:

* Initialize sitemaps. Add sitemap rewrite rules and query var
	 */
	function init() {
                global $wp_rewrite;
		$GLOBALS['wp']->add_query_var( 'sitemap' );
		$GLOBALS['wp']->add_query_var( 'sitemap_n' );

		$this->max_entries = ( isset( $this->options['entries-per-page'] ) && $this->options['entries-per-page'] != '' ) ? intval( $this->options['entries-per-page'] ) : 1000;

		add_rewrite_rule( 'sitemap_index\.xml$', 'index.php?sitemap=1', 'top' );
		add_rewrite_rule( '([^/]+?)-sitemap([0-9]+)?\.xml$', 'index.php?sitemap=$matches[1]&sitemap_n=$matches[2]', 'top' );
                $wp_rewrite->flush_rules();
	}

7. In the case you need to access my site, you can do it here

I expected the plugin to do this:
Basically I expected this part to work 🙂
I spent as much time troubleshooting it as it took me configure SEO for the whole site.

Instead it did this:
It made me feel insignificant, inferior and worthless.
OK, I’ll stop kidding, but I really need a help on this one. I’m just out of resources and don’t know what else I can try.

Thank you guys.

P.S. Yoast – great plugin, but please make this 404 error disappear.

http://wordpress.org/extend/plugins/wordpress-seo/