Please check and make sure the privatekey is not missing for this certificate.

 

The setup is actually trying to run below command and its getting failed.

Enable-ExchangeCertificate -Thumbprint $thumbprint -Services SMTP

 

1.Open MMC and add the Certificate Snap-In for the Local Computer account.

 

2.Double-Click on the certificate that has thumbprint AC3215B73FDE0CD05713575010C9FD0435EA1678Note: In 2008 it will be the certificate missing the golden key beside it.

 

3.Select the Details tab.

 

4.Click on the Serial Number field and copy that string.Note: You may use CTRL+C, but not right-click and copy.

 

5.Open up a command prompt session. (cmd.exe aka DOS Prompt)

 

6.Type: certutil -repairstore my “SerialNumber” (SerialNumber is that which was copied down in step 4.)

 

7.After running the above command, go back to the MMC and Right-Click Certificates and select Refresh (or hit F5 in the MMC)

 

8.Double-Click on the problem certificate. At the bottom of this window (General tab) it should state: “You have a private key that corresponds to this certificate.”

 

Now try to run the setup.