So Today, I attempted to access my NAS over SMB (\\files) on my network workgroup. The window hung for a moment, and a dialog I've never seen before when connecting to a share, with the title "Select Certificate" popped up. ultimately, I'm unable to access my shares from this box.

Select Certificate window

I can see that a certificate windows registered for my local user has expired. it was issued by me to me, the very definition of self-signed. The certificate has no trusted root certificate (not surprising). Windows tells me I have a private key associated with this certificate.

I did not knowingly create a certificate, and I've never known SMB to just fail every year just because a cert expired (or really even to require one at all, if you are not on a domain).

A reboot didn't clear the issue, and I'm having difficulties finding information on generating a suitable replacement.

Any ideas?


It appears I can get to shares using the FQDN, without any request for a certificate. DNS resolution works as well for hostnames as fullnames on my LAN, so I'm thinking something has remembered that destination, and needs to be flushed. any ideas what?

  • What are the Extended Key Usages of that certificate? – user1686 Apr 21 at 23:51
  • @user1686, ok I retract my last comment, I do see the cert in Certmgr, under the Personal keystore. It has no details on extended usages in the cert itself, and the certificates purposes are all checked. – Frank Thomas Apr 22 at 0:09
  • What is the NAS? Does it use Linux and Samba ? – harrymc Apr 25 at 14:15
  • its a Synology, so yes, linux and samba (DSM is up to date). I've set its min SMB spec to v2 amd max as v3. the users involved can login to the webportal, or access the shares via hostname from another workstation. – Frank Thomas Apr 25 at 16:04
  • 2
    Try to delete this login in Control Panel > User accounts > Manage your credentials (check both by IP and name files and inside both Windows Credentials and Web Credentials), reboot, then login again to \\files. – harrymc Apr 26 at 7:39

To make Windows forget a stored login :

  • Run Control Panel > User accounts
  • Click "Manage your credentials"
  • Find the login (identified by IP or its name files)
  • Look inside both Windows Credentials and Web Credentials
  • When found, click the down-arrow to the right of the credential
  • Click "Remove" to delete
  • Reboot
  • Login again to \\files.
  • Great find, thanks again! – Frank Thomas Apr 29 at 21:19

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