Getting 'An update error occurred. Try again"

I can't do a live update, I get the message 'An update error occurred'. Then an option to 'Try Again'.

I can't find any fixes online anywhere for this.

I'm using El Capitan on iMac.

I performed a Full Scan and Norton found no threats on my system.

I also have Net Nanny on my iMac, but this isn't anything to do with the live update problem.