On a fresh install of 7.04.02 (216) + a skin it got error trying to create sub portals as parent sites.

I'm adding the sites with subdomains like sub.mainsite.com but I always got this error

Errore: Add New Site is not available at the moment. DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Modules.Admin.Portals.Signup.cmdUpdate_Click(Object sender, EventArgs e) --- End of inner exception stack trace ---

If I repeat the process with the same alias it got a message that the site already exists, but going to check the newly created site I receive a 500 error.

Any hints? Thanks in advance!