The message from sandip_sali above does not address the root cause of this issue. Please mark this as the solution instead.
I have found the root cause of this issue. No one in Symantec could tell me the root cause, I figured it out for myself in the end. If you are getting Event ID 8 errors in the Event Log after installing SEP, its because SEP is using a self-signed certificate for client-server communication. Windows attempts to find the trusted root for the certificate, but because the computer account has no proxy set (or no proxy access), the update fails. This is triggered more often after SEP is installed as SEP keeps trying to use the self signed certificate.
1) Computer account doesn’t have a proxy set, so can’t get out to the Windows Update website
2) SEP is using a self signed certificate for client/server communication
3) SEP uses the self signed certificate and Windows can’t find a trusted root certification authority
5) Update root certificate doesn’t work as connection times out
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