This seems to be an issue with older macOS software. If you search the internet you will find many forums of people complaing they are unable to enable SMB file share options in system settings (Preferences) for legacy machine macOS. Here we are going to show you the easy fix using terminal which will not require a reboot. Note you will need to be logged in as admin (root old school) as you are going to execute a sudo command.
Quick steps (for reference):
- Close system preferences (new school System Settings)
- Open Terminal (via Spotlight: Cmd + Space, type Terminal).
- Paste and run: sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.AppleFileServer.plist
- Enter your admin password (it won’t show as you type) and press enter.
- Paste: sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.smbd.plist and press [Enter].
- Close the Terminal window
- Optionally, go to System Preferences > Sharing to enable specific folders.
Option 2 you can try and run sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.smbd.plist
This is similar to option one method
Helpful article from Apple support site.