Description

If you have Sitecore XP 9.1 installed by SIF 2.0, installation of XP 9.0 Update-2 may fail with the following error when SIF 1.2.x is used:

TerminatingError(New-SignedCertificate): "Cannot process argument transformation on parameter 'Signer'. Cannot convert the "System.Object[]" value of type "System.Object[]" to type "System.Security.Cryptography.X509Certificates.X509Certificate2"."
Install-SitecoreConfiguration : Cannot process argument transformation on parameter 'Signer'. Cannot convert the "System.Object[]" value of type "System.Object[]" to type "System.Security.Cryptography.X509Certificates.X509Certificate2".

If you remove the certificates, installation can proceed successfully but the Sitecore XP 9.1 instance itself will be broken with certificate errors.

Solution

Perform the following steps to resolve the issue:

1. Edit the installation script for Sitecore XP 9.0 Update-2, and add the "RootCertFileName" parameter to the section that generates the certificates, using the xconnect-createcert.json parameters. The RootCertFileName parameter can have any unique value. For example:

   # Install client certificate for xconnect
   $certParams = @{
     Path = "$SCLocation\xconnect-createcert.json"
     CertificateName = "$prefix.xconnect_client"
     RootCertFileName = "SIF121Root"
   }
   Install-SitecoreConfiguration @certParams -Verbose

2. Ensure that SIF 1.2.x is the version that is active in the PowerShell session with following command:

   Import-Module -Name SitecoreInstallFramework -RequiredVersion 1.2.х

3. Run your installation script as usual.