KB4503276 Disconnects Mac clients connecting to SMB File Shares

KB4503276 Disconnects Mac clients connecting to SMB File Shares

After installing KB4503276 on June 12, 2019, our Mac clients can no longer connect to SMB file shares .

Mac clients which mount SMB volumes on a Windows PC may no longer be able to open the Windows shares.

To overcome this issue either uninstall the Windows KB4503276 update or manually re-enable SMB on the Windows computer by following the below.


Windows 7

Open Regedit

Navigate to the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

Ensure SMBV1, SMBv2 and SMBv3 are all enabled by having the key set to 1

Restart the computer


Windows 10

Open search bar and type: "Turn Windows Features on or off"

Ensure Tick Box for "SMB 1.0/CIFS File Sharing Support

Restart the computer



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