Sitemap gives 404

I had the same problem and added the following to beginning of .htaccess

# 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

What theme are you using?

I already have this at the end of the .htaccess file:

The only thing you should have in your root htaccess file is one instance of the BEGIN WordPress to END WordPress Rewrite code. This is assuming that based on this other BPS plugin forum topic you posted: https://wordpress.org/support/topic/completely-remove-bps?replies=6 that you have removed/deleted the BPS plugin.

You have the Adaptive Images for WordPress plugin installed, which automatically creates this htaccess code in your root htaccess file when you save settings in that plugin. That code is added at the top of your root htaccess file and I believe that is ok, but have not tested it. Your entire root htaccess file code should be this below:

# BEGIN Adaptive Images
#=======================

<IfModule mod_rewrite.c>

    RewriteEngine On

    # Watched directories
    RewriteCond %{REQUEST_URI} /wp-content/uploads [OR]
    RewriteCond %{REQUEST_URI} /wp-content/themes

    # Redirect images through the adaptive images script
    RewriteRule \.(?:jpe?g|gif|png)$ /C:\xampp\htdocs12\demo5\wp-content\plugins\adaptive-images/adaptive-images-script.php [L]

</IfModule>

# END Adaptive Images

# 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

Personally if I was using that plugin or that plugin’s code I would customize it and combine it something like this below, but I have no idea if that plugin will allow that or not. And a possible problem that I noticed when testing that plugin is that on a XAMPP server the full path in the RewriteRule is created and your code shows a relative path. That may because it is XAMPP.

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# Watched directories
RewriteCond %{REQUEST_URI} /wp-content/uploads [OR]
RewriteCond %{REQUEST_URI} /wp-content/themes
# Redirect images through the adaptive images script
RewriteRule \.(?:jpe?g|gif|png)$ /wp-content/plugins/adaptive-images/adaptive-images-script.php [L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress