File Sharing sometimes fails in macOS High Sierra after installing Security Update 2017-001. This should fix it...
Open the Terminal application (in Utilities folder, inside Applications folder). Enter this command: sudo /usr/libexec/configureLocalKDC Hit the return key. Enter your administrator password to authenticate with sudo. Quit out of Terminal.
Now try an AFP or SMB file sharing connection, which should now work.
My latest blog post: Sheeple: Are they succumbing to fake news, misinformation, and propaganda. (posted 2025-09-24). My latest podcast: OJB's Podcast 2029-09-09 Kiwi Values.