There are reports all over the web about the KB3093266 update failing. I have this issue too. Numerous “fixes” have been posted and not a single one of them works for everyone. Some folks are manually downloading this update from non-official sources. I advise against it. Relax folks, it ain’t that important. Microsoft will fix it.

***UPDATE
This morning after this update failed again I decided to try sfc /scannow. I know, I know, we all hate that suggestion.
Well,
it worked! (I HATE that it worked). PLEASE let me know if this did or did not work for you.
Open an Admin command prompt (find option by pressing Windows + X keys) > type sfc /scannow and let it run, reboot when finished > manually run Windows Update > success
(note – CBS.log was FULL of errors.)