How to resolve Google Drive file sync issues - red cross mark?

Google Drive is a cloud storage available to all Google Users. If you have a Gmail address, you have Google Drive access too. Every user gets a basic 15GB storage, which is quite sufficient to store your personal files. If you are already using Google Drive, you may already know that it is accessible at https://drive.google.com. Google Drive also has a "Backup and Sync from Google"