Last week I had to upgrade a few Exchange 2013 CU15 servers to Exchange 2013 CU18. In a typical scenario upgrading to a newer Cumulative Update it’s not a big deal, not even when skipping a few versions, but in this scenario most likely you will hit the following error message:
It fails during the Prerequisite Analysis with the error message
“This computer requires .NET Framework 4.6.2 (https://support.microsoft.com/kb/3151802). For more information, visit: http://technet.microsoft.com/library(EXCHG.150)/ms.exch.setupreadiness.MinimumFrameworkNotInstalled.aspx
The Exchange Server setup operation didn’t complete. More details can be found in ExchangeSetup.log located in the (SystemDrive):\ExchangeSetupLogs folder.”
Exchange Server 2013 CU18 requires the .NET Framework 4.6.2 for installation which was obviously not installed on these servers.