A customer called me this morning unable to access network shares from Windows 7 machines that have been working for years. The error message was:
Windows Cannot Access \\COMPUTERNAME
Check the spelling of the name. Otherwise, there might be a problem with your network.
This error is caused by windows update KB4480970
As of right now, you can remove the update or workaround the problem by using an IP address instead of a machine name.
Uninstall KB4480970 to restore access to network shares
The quickest way to uninstall the update is from an elevated command prompt:
wusa /uninstall /kb:4480970 /quiet /warnrestart
Workaround network share problems caused by KB4480970
You can still access the shares with this update installed by using the IP address of the machine name, but this could be very inconvenient. Example:
Instead of \\Machinename\sharename you could use \\192.168.10.10\sharename
Hopefully Microsoft will correct the issue as quickly as possible as this will cause the same problem on Windows 7 and Windows 2008 r2.