Problem solved with this:
# BEGIN WordPress
<IfModule mod_rewrite.c>
Options +FollowSymlinks
RewriteEngine on
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>
# END WordPress
Hello. I have got this same problem. I have researched but I have not found any solution.
At the beginning my empty htaccess file did not update properly, after changing its permissions, it is updated by WordPress but I got a 403 error and can not access to the blog.
When WordPress does not update the htaccess file because of file permissions, it tells me to ad this to the file:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>
I have done this too, but it seems everytime htaccess is modified I can not access to the blog. While the file is blank there is no problem.
Any ideas?