I had a site that required a single quote like O'Hara.
When I saved the change, the display stayed as "No Site Name", but did not give an error.
So I tried to put the site name in via the configuration file. When that configuration was applied, the GUI indicated that Site Name had an "error 1".
So I re-entered the name as "OHara", and it took.
So the GUI should indicate that the single quote (and possibly other characters) are not allowed, instead of passively going back to "No Site Name". Or maybe it could just drop the illegal characters.