I am having this exact same issue.  I know it's not username, password, or pin, because when one of those is wrong, I get the typical incorrect info message.  I also know I am not locked out, since the last time I tried was over two and a half hours ago.  Also, if I click on "Control Panel" after getting this message, I am not returned to the login screen.  The message stays up, but now I have "Logout" as an option on the left side menu.  I have to click it to get back to the login screen.
 
	Message with correct info is:
 
	"Oh. Something went wrong. :(  Internal Server Error"
 
	Message with incorrect pw:
 
	"Invalid credentials"
 
	Message with incorrect pin:
 
	"The verification code is not valid"