Share Files Between Windows and a Mac over SMB

A share that allows Everyone is the fastest way to fail on a Mac, because guest access is disabled on macOS by default. Name the account that will connect.

New-Item -ItemType Directory 'C:\Shares\Exchange' -Force | Out-Null
New-SmbShare -Name 'Exchange' -Path 'C:\Shares\Exchange' -FullAccess 'PC01\bob'
Grant-SmbShareAccess -Name 'Exchange' -AccountName 'PC01\bob' -AccessRight Full -Force
Get-SmbShare -Name 'Exchange' | Select-Object Name,Path,Description

Signing is mandatory in newer builds, and SMB1 is gone. macOS supports SMB2 and SMB3, so a modern Windows share works without legacy protocols.

Get-SmbServerConfiguration | Select-Object EnableSMB1Protocol,EnableSMB2Protocol,RequireSecuritySignature,EncryptData
Get-NetFirewallRule -DisplayGroup 'File and Printer Sharing' | Select-Object DisplayName,Enabled,Profile -First 5
Get-NetConnectionProfile | Select-Object Name,NetworkCategory

**Finder > Go > Connect to Server** takes the SMB URL. The credentials are the Windows account name and its password, not the Microsoft account email unless that is how the account is set up.

# on the Mac: Finder > Go > Connect to Server
# smb://PC01/Exchange
# user name: PC01\bob  (or bob)   password: the Windows password
# check the Windows side after the connection:
Get-SmbSession | Select-Object ClientComputerName,ClientUserName,NumOpens

macOS has its own SMB server. Enable File Sharing, add the user, then map the share on Windows with the Mac's short name or IP.

# on the Mac: System Settings > General > Sharing > File Sharing > Options
# enable SMB sharing and tick the account
net use Z: \\192.168.1.60\bob /user:bob
Get-SmbMapping | Select-Object LocalPath,RemotePath,Status

Windows caches the Mac credential and keeps retrying it. Clearing the cached entry is the fix when the password changed on the Mac.

cmdkey /list | Select-String -Pattern '192.168.1.60'
cmdkey /delete:192.168.1.60
net use Z: /delete
net use Z: \\192.168.1.60\bob /user:bob

Create a file on each side and read it from the other. Permissions metadata differs between APFS and NTFS, so a file that copies but cannot be written back is a permission issue, not a protocol one.

New-Item 'C:\Shares\Exchange\from-windows.txt' -Value 'ok' -Force | Out-Null
Get-ChildItem 'C:\Shares\Exchange' | Select-Object Name,Length,LastWriteTime
Get-SmbSession | Select-Object ClientComputerName,NumOpens,Dialect