Why are keys failing to update at Mekorma Registration? I am receiving the warning: Error 16 Contact Mekorma Support. Cannot communicate with web service.

Having FIPS (Federal Information Processing Standard)  enabled prevents Mekorma web services communication needed for registration key retrieval. In previous cases we found that disabling FIPS allows Mekorma web services key registration retrieval method to function as expected.

Enabling/Disabling FIPS in Windows 
We recommend  the use of the Group Policy Editor (gpedit.msc), setting the option to "Disabled" as described in the following Microsoft article: 

https://learn.microsoft.com/en-us/archive/msdn-technet-forums/209e25be-0925-484e-ac10-736823e2b9f3