If you are experiencing 404 errors with pretty permalinks and a white screen when you upload images, mod_rewrite may not be enabled in Apache by default. Mod_rewrite is an extension module of the Apache web server software which allows for “rewriting” of URLs on-the-fly. It’s what you need to make pretty permalinks work.
WordPress Multisite networks usually experience this but it can also occur on shared hosting providers or after a site migration or server move.
Reset your permalinks through Settings > Permalinks. If this does not work, you may have to edit the .htaccess file manually.
# 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
If you are not familiar with editing your .htaccess file, contact your hosting provider to ask them to turn on mod_rewrite rules.
