With the newer versions of Ektron, we have seen the below error occur with Windows Server 2012 R2. This issue has shown in the registration log during a Solr install, as well as a rebuild of 9.0x. The reason coming from on the 2008 R2 server is that this key was disabled. It was enabled on the 2012 instance.

DefaultCmsService.Get: [InvalidOperationException] This implementation is not part of the Windows Platform FIPS validated cryptographic algorithms.
   at System.Security.Cryptography.MD5CryptoServiceProvider..ctor()

Go to Start > Run and type in "regedit" without the quotes. Then press Enter or click OK. Drill down the following path

HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Control > Lsa > FipsalgorithmPolicy

Disable registry key (set to zero), by changing “Enabled” to “Disabled”