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I tried logging in from a Mac to a PC and I get a error message saying it could not connect because the data can not be read or written. What should I do?

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Following the exchange from and , the message "could not be read or written" when mounting a Windows share from macOS typically points to one of three root causes: permission/ACL mismatch on the Windows side, the Mac is being authenticated as a guest/anonymous user, or a protocol/firewall/networking problem. Quick checks that resolve most cases are listed below.

Confirm network and connection method first. Use the server IP in Finder → Go → Connect to Server with an explicit SMB URL such as smb://192.168.1.10/share or smb://username@192.168.1.10/share so authentication is explicit (guest mounts often deny write access). Verify basic network reachability (ping the host) and try the IP rather than a hostname to rule out name resolution issues.

Verify Windows share and file-system permissions. Both Share permissions (Sharing → Advanced Sharing → Permissions) and NTFS Security permissions (Security tab) must grant write/change rights to the same account used to authenticate. A share set to Read-only or a mapped account that Windows treats as Guest will produce the exact "cannot be read or written" result even though the share is visible. Also confirm the share drive isn’t full and not marked read-only.

Check firewalls, SMB dialect and virtualization. Temporarily allow File and Printer Sharing or disable the Windows firewall to test, and ensure TCP/UDP ports for SMB (TCP 139/445, UDP 137/138) aren’t blocked. If the Windows host is inside a VM, make sure the VM’s network is bridged to the LAN (NAT can block direct SMB access). On modern systems, SMB protocol version mismatches matter: try both smb:// and cifs:// and consider updating servers/clients rather than re-enabling insecure SMBv1.

Useful diagnostics: on macOS run the following to list/view shares and mount state:

smbutil view //username@host
smbutil statshares -a

If the problem persists, collect the macOS and Windows versions, exact error text, the authentication mode used, and Windows share/security settings — that information is essential for deeper troubleshooting. For an alternate transfer method, SFTP/FTP or a temporary SMB client replacement can confirm whether the issue is SMB-specific.

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Member Avatar for MAD_DOG

What piece of software are you using to connect from OS X to Windows?

Member Avatar for Nemesis

I am using MAC OS X latest one and it has SAMBA on it already. It just says that it can not be read or written.

Member Avatar for MAD_DOG

How did you log in Windows? & how do you want to log in windows? Are you using Virtual PC? Let me know

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