"The handle is invalid" when accessing share over network.
I have a client with a Windows 7 pc with a folder that is shared on their network (Workgroup). Sometime last week, after Windows Updates were installed, the other pcs on the local network could no longer browse the network or map a network drive to the Windows 7 network share.
Upon further investigation I found that the pcs were able to ping the Windows 7 by name and ip address. This ruled out DNS issues. I also temporarily turned off the Norton Firewall software to rule that out as well. The error that was displayed was either "The handle is invalid" or "Unknown Error" from other devices on the network.
After some research it appears that KB4480970 is breaking network connectivity on Windows 7 pcs.
Two possible fixes I found were to remove the KB4480970. I generally do not like removing windows updates unless its a last resort so I opted for the second option. The other fix was to install a hot fix that resolves the problem from the first update. After installing the hotfix listed in the below link, pcs were immediately able to access the Windows 7 PC network share again.
This may not work for everyone but It Fixed it for me.
If anyone has an alternate fix please post it in the comments.