While finishing the installation of the XenDesktop controller while building a XenDesktop 7.12 environment, I ran into the message “This implementation is not part of the Windows Platform FIPS validated cryptographic algorithms.” From there, I could not continue the installation.
Researching this issue, I came across a Citrix article applicable to Provisioning Services, CTX1388823 - Provisioning Services Database Unable to Configure, with the same error message. The article refers to Provisioning Service database unable to be configured. It explains that this can occur when the server has been hardened for security purposes enabling FIPS.
I wondered if this same would apply to my issue reported from the XenDesktop controller, since the messages were identical. As it turned out, my customer had hardened the servers for security purposes and the FIPS registry key was enabled. After disabling the registry key, I was able to continue with the installation of the XenDesktop controller.
Set the registry key to:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\FipsAlgorithmPolicy]
"Enabled"= Dword:0000000x
The next day after the XenDesktop Site had been configured with four controllers, I started to receive the following message when launching Studio:

Checking the box and continuing resulted in this:

When you upgrade, the process finishes successfully but you are still in the same window.
During the night, the GPO enabled the FIPS registry key once again. Once we manually disabled the registry key, the Studio console launched normally.