I had a old site in my multisite setup that had not been used for 2 years. I had a person ask if they could rename their site url and use the site url that had gone dormant. I said sure. So I deleted the old named site from the network and then renamed the other site to the "new" name. Immediately, I got a 404 error for the newly named site. The database still has their content and the new site name is listed in the network admin area, but I cannot get the site to load. I've been able to revert it to the original name, but that didn't work either.