The same problem of here: Error while building project
I’ve already wasted more than 6~8 hours trying to solve it and nothing
Hello, The build was failed: Login – Vercel because The specified Root Directory <> does not exist"
Hi, Zaia! Welcome to the Vercel Community 
Could you try going through some troubleshooting steps for build errors documented here?
For that generic error (my first message):
An unexpected error happened when running this build. We have been notified of the problem. If you have any questions, please contact Vercel Support Help”
How should I proceed?
The only thing I hadn’t done was “npm install -g vercel”
Even so, the deploy doesn’t work.
Could you share a minimal reproducible example with us, Zaia? Would help us find the root cause. 
Appreciate your patience!