After an update, one of the “Windows 10” PCs in my network could no longer successfully share its properly configured folders, which were working before the update.

When trying to access paths such as

\\computerName\shareName

the access would fail because of “no permission”.

NET use

commands would cause “System error 1219”.

All machines, including the source machine, were able to list the shared resources at

\\computerName

But no machine, including the source machine (!), were able to browse inside any resource.

Searching for the expression “windows 10 cannot access its own shared folders”, regardless of search engine, gives useless top results. A bad job from all search engines, also seen when one tries to find unbiased product reviews. The results from microsoft.com, spiceworks.com, tenforums.com, etc., are spectacularly bad and incredibly frustrating, with long threads of diagnosing rubbish, all for nothing, with the support effort typically ending in a “did not work” reaction to the scripted suggestions.

In the end, I found that the error was because of “UAC” (“User Access Control”). That feature had been re-enabled by the Windows update. Disabling UAC – a functionality that I find annoying and of doubtful merit – fixed the issue.

Such was the annoyance and the break in productivity, due to an undocumented side effect of a feature causing what it should not cause, that I researched and wrote a PowerShell script to “run everything as administrator”. This solution might require a system restart, but I left the line that does so commented. Just remove the sharp (#) from the line

#shutdown -r -t 0

, if you want the script to restart the computer, instead of doing it yourself, on your own time.

#EnableLUA: http://technet.microsoft.com/en-us/library/ff715520.aspx
Set-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System" -Name "EnableLUA" -Value "0" #Default value is 1

#The following is equal to the Security Policy "User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode" = "Elevate without prompting"
#http://msdn.microsoft.com/en-us/library/cc232761.aspx
Set-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System" -Name "ConsentPromptBehaviorAdmin" -Value "0" #Default value is 2

#The following is equal to the Security Policy "User Account Control: Allow UIAccess applications to prompt for elevation without using the secure dekstop" = "Enabled"
#http://technet.microsoft.com/en-us/library/dd835564(v=ws.10).aspx
Set-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System" -Name "EnableUIADesktopToggle" -Value "1" #Default value is 0

#Reboot server
#shutdown -r -t 0