How to fix: "Google Safe Browsing Service is Unavailable" Error in Safari
1. On the Finder Menubar, click "Go".
2. Then click, "Go to Folder".
3. Type in: /private/var/folders
4. There will be a few folders to search through. Open them up and search for a folder named com.apple.files and open it.
5. Find, and open the folder named , com.apple.safari
6. In this folder, there should be a folder named, safebrowsing.db
7. Send it to the trash and delete it. This will force Safari to rebuild the file.
8. This should fix the problem. Check back in a day or so to test. Note: This file is not updated every day.