After installing KB4480970 I cannot access shared folders or printers [duplicate]

I just installed KB4480970 on my Windows 7 computer LAB-PC. Now none of the other machines on my network can access the folders and printer I have shared from this computer.

Everything was working fine before the update. Turning off the Windows firewall didn't help. I can ping LAB-PC from other computers.

If I try to access my share "Test" on LAB-PC from another computer by typing \\LAB-PC\test into Explorer's address bar, I get the error:

Windows cannot access \\LAB-PC\test

I tried mapping a drive to LAB-PC by running net use Z: \\LAB-PC\test and got the error:

System error 6 has occurred.

The handle is invalid.

I'm running Windows 7 Pro 64-bit. My computer is not in a domain. How can I fix this?

This is a known issue caused by the January 8, 2019 Windows Update KB4480970. According to Microsoft this update introduces the following issue:

Local users who are part of the local “Administrators“ group may not be able to remotely access shares on Windows Server 2008 R2 and Windows 7 machines after installing the January 8th, 2019 security updates. This does not affect domain accounts in the local "Administrators" group.

On January 11 Microsoft released hotfix KB4487345 to resolve this issue:

This update resolves the issue where local users who are part of the local “Administrators“ group may not be able to remotely access shares on Windows 7 SP1 and Windows Server 2008 R2 machines after installing the January 8th, 2019 security updates. This does not affect domain accounts in the local "Administrators" group.

This hotfix is not being distributed via Windows Update. Instead, you must download it directly from the Microsoft Update Catalog website.

Install this hotfix on the computer hosting the network share(s) that users are not able to access. According to my testing it's not necessary to install it on computers from which one is trying to access the shared folders or printers.