We got this answer from our Symantec contact: SEP 12.1.6 MP4 build 12.1.6860.6400 failed sometimes during installation if Comodo code signing certificate (trusted root certificate) was not installed. This was corrected in SEP 12.1.6 MP4 build 12.1.6867.6400. ...
Saw that. I guess if I'm not having the certificate problem on installation, that I don't need to upgrade again? But then again, it would seem likely that a certificate problem would be a security problem and would be cause enough to warrant an upgrade ...
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