Cannot log in via

I have access to classic Warcraft 3 through a preorder for Reforged. I log in through my Blizzard account credentials. Today, when trying to log in after a few months, the app will not log in. I am entering my credentials correctly; the same credentials work to log me into Battle-dot-net app and Blizzard-dot-com. However, the classic Warcraft 3 app returns the message “An Error Has Occurred”. How do I regain access to my classic Warcraft 3 game?

Edit 3/29/19: solved my own issue. Had to update the game. Launching the application didn’t prompt an update; had to open the Warcraft II Launcher to get an update prompt. After updating, credentials let me access the game.