Error message - Cannot import as there already is a certificate
When importing a certificate in the Exchange Management Shell, the following message may appear:
Error Message - Cannot import as there already is a certificate with a thumbprint of ...
This error message appears when importing a certificate in Exchange where the certificate is already known in IIS.
You will therefore only have to activate the certificate using the following command:
Enable-ExchangeCertificate -Thumbprint "number series thumbprint" -Services "POP, IMAP, SMTP, IIS"
The Thumbprint can be found by double-clicking on the certificate and scrolling down on the Details tab. See also: