[mike86]

I've ruled out DNS as I've tried all manner of DNS servers over the last 24 hours. As I say, it's affecting multiple customers. Most sources indicate this is a TLS error and sometimes even indicative of a MITM attack.

Error -1012 is kCFURLErrorUserCancelledAuthentication which can relate to an invalid certificate.

Given the above, my suspicion is that it could be something like VM's anti-piracy system gone haywire. That breaks TLS connections as it inspects the SNI header in a HTTP request and then tries to serve up their anti-piracy page if it's a blocked site (obviously VM's server can't serve up a valid TLS certificate for the domain). Essentially, they perform a MITM attack.

We can expect Apple's software update process to be good enough to abort if it detects an invalid TLS certificate, which is what seems to be happening. But Apple's TLS certificate is valid, because other users on other ISPs aren't affected.

Also I should add that an affected Mac that could not perform updates while connected to Virgin Media was able to successfully do so when tethered to an EE connection, so this rules out anything specific to the computers.

---------- Post added at 16:00 ---------- Previous post was at 14:21 ----------

Seems to be resolved now. What a massive waste of time this has been, and Virgin's support has been spectacularly awful.