Lync Certificate Replacement

★☆As soon as the new certificate is assigned new phone calls will begin to disconnect. To fix it restart ‘Lync Server Mediation’ service or reboot the server.★☆

1. Remote Desktop to the Lync Server in question.
2. Open the Lync Server Deployment Tool.
3. Install or Update Lync Server System.
4. Request, Install or Assign Certificates –> Run Again
5. Request a new certificate from the Lync Deployment Wizard
6. Once you have the new certificate, import it.
7. Once imported click the current certificate you want to replace and then click Assign.
8. Follow through the wizard, selecting the the new certificate.
9. Reboot the system to activate the new certificate.

For 2017-2019 certificate I had to “repair” the certificate after importing it before it would be available to assign.

certutil –repairstore my “serialnumber”

http://howdouc.blogspot.com/2010/12/repairing-invalid-certificate-for.html