To reproduce:

1. on public instance go to /modules/admininterface/VirtualURIMapping
2. edit the default mapping to have following:
fromURI -> /
toURI -> redirect:/index.html

After going to public instance (like http://localhost/magnoliaPublic/) I get a 404 page

Cause:

default URI mapping is missing class -> info.magnolia.cms.beans.config.DefaultVirtualURIMapping node date

Workaround:

add info.magnolia.cms.beans.config.DefaultVirtualURIMapping to class node data in default uri mapping

The bootstrap file needs to be adjusted