hi, I have the same problem with SEP some days ago and, this particulary windows defender update.
I just remove SEP, reboot my computer, open windows defender and click in "manual" definition update.
after some time this problem was resolved
try do this and share the solution with me, if possible
I did try uninstalling SEP several times & the problem is resolved.
Googled the error, it seems many people are facing the same but still can't find a proper way to fix..