Symptom

STAgentUpdater.log

WinTrustVerifier.cpp:195 Certificate verification failed with error : -2146762748

Cause

The OS is unable to verify the digital signature. The specific error is -2146762748 which is a Mircosoft error that translates to "The subject is not trusted for the specified action"

Resolution

1) Update the Root Certificate on the client machine. You can update it manually or run a scan with Security Tools enabled against it. It's going to be MSRC-001 or MSRC-002.

2) It's possible the System Account (used to run the agent services) is having issues on the machine. You could attempt to run the agent services as a domain account as a test.

Updated:

3) it is also possible that computers were missing root CA cert VeriSign Universal Root Certification Authority. While Windows was attempting to connect to Microsoft Update to obtain this cert automatically during update install and failing. Allowing ctldl.windowsupdate.com through the firewall and network security appliances, the issue could also be corrected.