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On a Windows Server 2008-based computer, when you try to install the certification authority (CA) role, you receive the following error message:
Cannot install Certification Authority. Certification Authority cannot be installed on this computer
This problem occurs in the scenario when only the CA Web Enrollment service was installed previously under the Active Directory Certificate Services (AD CS) role, and then the CA Web Enrollment service was uninstalled. In this scenario, the following registry subkey still exists in the registry:
However, this registry subkey should have been deleted.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
To resolve this problem, check whether the following registry subkey exists:
Windows Server 2008 Standard, Windows Server 2008 Enterprise, Windows Server 2008 Datacenter, Windows Server 2008 Standard without Hyper-V, Windows Server 2008 Enterprise without Hyper-V, Windows Server 2008 Datacenter without Hyper-V, Windows Server 2008 for Itanium-Based Systems