Here are some things to consider before installing WPMultiSite.

Permalinks

All site using a single installation of WordPress must use the permalinks. Make sure when you create a new site you set the permalink setting.

Site Maps

If you use the ‘Google XML Sitemaps’ plugin, you can manually set the location of the sitemap file in the plugin configuration.

favicon.ico

All sites will use the same favicon for now.

robots.txt

All sites will use the same robots.txt file for now.