Ssl – How to manually install a SSL .cer on an IIS 6 site without CSR

The error usually occurs because you have deleted pending request of the certificate. The only recourse is to request a new certificate and completely finish the request before anything "security related" is changed on the machine.

Chances are the private key still exists, but you will have to use certutil to repair the association. I've had to do this a few times myself. The below is from HERE:

To install a Web server certificate that lacks a pending certificate request 1. Click Start, point to Run, type cmd, and then click OK.

2. Navigate to the directory where Certutil.exe is stored; by default, this is %windir%\system32.

3. Type the following command at the command prompt: certutil -addstore my certnew.cer where certnew.cer is the name of the certificate you received from the certification authority (CA). You should see the following message: CertUtil: -addstore command completed successfully.

4. Navigate to the directory where you stored the certificate you received from the CA. Right-click the certificate and then point to Properties.

5. Click the Details tab and select in the Show drop-down list.

6. In the Field list, select Thumbprint to display its value in the view pane.

7. Select the Thumbprint value in the view pane and then click CTRL+C.

8. Return to the command prompt window and type the following command: certutil -repairstore my "thumbprint" where thumbprint is the value of the Thumbprint field. Be sure to type the double quotes as part of the command. If the command is successful, the following message is displayed: Encryption test passed CertUtil: = repairstore command completed successfully.