The error: A folder shared from a Mac via File Sharing is visible or accessible from other Macs, but Windows clients either can't see it on the network or get an authentication error trying to connect.
Environment: Any current macOS version with SMB file sharing enabled, mixed Mac/Windows environment.
Why this happens: macOS supports SMB (the protocol Windows actually uses) alongside its own native AFP-era conventions, but a few macOS-side defaults — requiring a specific SMB authentication method, or a user account whose "share password" (a separate, SMB-specific credential macOS maintains) hasn't been set — block Windows clients specifically while Mac clients connect fine using different assumptions.
The fix:
- Confirm SMB sharing is actually enabled (not just File Sharing generally): System Settings → General → Sharing → File Sharing → Options, and confirm "Share files and folders using SMB" is checked for the relevant account.
- Re-enter that user's password in the sharing options specifically — macOS stores a separate SMB-hashed credential that isn't automatically kept in sync with a regular password change.
- From the Windows side, connect by IP directly (
\\192.168.x.x\sharename) rather than by name first, to rule out a name-resolution issue versus an actual permissions/protocol issue. - Check the Mac's firewall isn't blocking incoming SMB (port 445) if direct-IP connection also fails.
One thing worth knowing: the separate SMB password issue catches people specifically after a normal macOS password change — re-entering it in the Sharing pane afterward isn't optional, even though nothing in the UI clearly prompts for it.