File sharing broken after installing Security Update 2017-001 I've spent all day so far trying to resolve this. File sharing just doesn't work any more!

I am now fairly certain that installing Security Update 2017-001 for macOS High Sierra to fix the “root” vulnerability problem (see: https://www.imore.com/macos-has-root-bug), is the cause of my file sharing problem! C'mon Apple, where's your quality control!

Does anyone know how I can fix this?
Apple has already issued a quick fix to this. Follow these steps:


Launch the Terminal app (usually found in the Utilities folder within your Applications folder)
Copy the following command and paste it into Terminal:


sudo /usr/libexec/configureLocalKDC


Press enter
Enter your Admin password (Note: You won’t actually see the cursor move as you enter your password)
Press enter


For more info: https://support.apple.com/en-us/HT208317