I have same problem, using NIS ver 20.3.1.22
LiveUpdate started failing 8 days ago but no pop-up to warn me, until Windows Security Center reported NIS definitions outdated! Running Vista SP2 32-bit.
Since WSC warning, I've been trying LiveUpdate all evening of June 12 & continuing until 2am MDT June 13, with constant failures. Finally had to manually download latest Definitions & run the exe file.
HOWEVER, LiveUpdate still fails "with unknown error". AutoFix doesn't solve the problem; it simply reports "Conflict with MalwareBytes". (I understand from these forums that this conflict is no longer reported after installing NIS Update patch 20.4.0.40 but suspect this won't solve the LiveUpdate fail.)
I've PMed Tony Weiss for the Update patch (as suggested in his post of June 12) and, after install & reboot, will report if this solves my LiveUpdate problem.
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