I cannot sign into the App store. Any time I attempt to I get the same error I have tried literally everything I can think of to include deleting my login information for the app store and and reentering it entirely. Unfortunately I cannot seem to find a solution despite the multiple forums I have encountered. Does anyone have any idea as to how to fix this issue?
I am sorry to tell you, that is normal.

In times of new product release (OSX Mojave), they servers just get flooded with requests.

You are connected to App Store, but ca not pass the Log-In server.

It says, an Unexpected Error ?, 

if anything is wrong with you profile or your log-in information it would tell you that.

The problem is not on your side !

Just have to keep trying.