UPDATE: Blog comments are awesome. Just to stop you from having to look any further, Darren Shetler explains in the comment section (and I’ve confirmed) that the way to fix this is to:

1. Go into Device Manager
2. Delete the network devices – do NOT uninstall their drivers when asked!!!
3. Run “Scan For Hardware Changes” to add the network devices back to Windows

Afterwards, everything worked with an admin account, a regular account (prompts for admin credentials) and still worked after a reboot. If you want to be careful, do this to only one network interface, and confirm that it’s back working before you do the rest; that is, don’t get rid of your otherwise-functional WiFi and wired connections at the same time. Thanks for posting this, Darren!

Follow this Windows Insider Program forum thread for future developments: “Cannot open network connection properties after 10041 update”

Aleksandar Nikolic (co-founder and editor of powershellmagazine.com) asked the community if anyone else on the 10041 build of Windows 10 Technical Preview (pushed mid-March 2015) was getting “An unexpected error occurred” when we tried checking or changing the properties of a network connection. I checked with both a regular account (which should have prompted me to enter an admin account’s password) and my admin account, and got the same thing both times:

An unexpected error occurred. Very helpful.

However unenlightening that was, it was still better than the absolute nothing that happens when I tried disabling/enabling network devices or clicking “Diagnose this connection” – was it registering that I was clicking at all?

Fabien Didot joined in the thread to let us know that PowerShell cmdlets Get-NetAdapter and Get-NetIpAddress work, and I can confirm that they do from both a regular and an admin account. However, Disable-NetAdapter and Enable-NetAdapter fail from both with an access denied error – expected behavior from a regular account, but certainly not from an admin account. Helps if you start PowerShell using “Run as Administrator” 🙂 Totally works that way!

As far as other reports of this, I’ve turned up the Windows10 subreddit and a Guru3D thread.

If anyone else with the 10041 build could please try enabling or disabling a network interface with PowerShell, please let me know how you get on – is it just me, or are others experiencing this? Again, helps if you remember “Run as Administrator”!

Looks like it really is just the GUI.