New subdomain sites 403 & 404 errors

Hello

I have recently set up a multisite with subdomains and tried to follow all the codex instructions.

However, when I add a new site e.g. footsteps.peacehub.org.uk I get a 403 Forbidden error (plus a notice ‘Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.’) When I try to go to the dashboard I get a 404 Not Found error.

This applies to all subdomain sites that I create. The parent site (peacehub.org.uk/) is unaffected. My host is using a Linux server with Apache.

Based on advice from similar posts here I’ve checked that mod_rewrite is enabled (it is) and tried adding Options +FollowSymLinks to .htaccess, which caused the whole site to give a 500 Error.

This is what’s currently in my .htaccess:

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

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]
</IfModule>
# END WordPress

Any help gratefully recieved!