By now Riot probably noticed the Increasing Amount of People complaining over the Login Que. And especially these "Unexpected Errors" which are most likely the respond to a "Full Server". Because I noticed the Unexpected Error to happen when my Position in Que was at 1. It happend to several of my friends aswell. So I simply Assume the Server is Full and the Moment your turn comes to "Login" and the Respond from the Server is "Sorry we Have no Capacity Left" you'll just get the prompt "Unexpected Error" as the Login Systems "fails" to Log you in. And since that is usually not happening the System thinks that something went Wrong.
Anyway. I think, Riot should seriously Take PBE Down until they have more Ressources or can Run even if just temporarily a Second Server.
I rather wait 2-3 Days but have a "Clean" Login Que. Than having to sit in Que for several Hours or even nearly half a Day, to just have a Chance of getting Into the Server because when my turn comes and the server capacity is Full I will just get Prompted the Error and get Kicked out.
Also due to the "Full" Server, the Shop often doesn't respond or Open at all. Hex Tech Craft bugs out and causes Client Crashes resulting in your Log Out. (Happend to me in the Night when I finally got in after 6 Hours Que only to find a not-working Store and a bugged Hextech Craft System to crash my client and kick me out.)
Idk if people agree with me here. Or experience similiar stuff. But I think, people are more willingly to wait 1 or 2 more Days or even 3 days hell even a Week for a properly working Que and way more ressources on the Server. Atleast I would, cuz then I atleast know "It's not there even IF I did Login."