NSURLErrorDomain error -1012

Please read this whole message before doing anything.

Thanks to Linc for the info. I stopped reading at "third-party software," somehting which I've noticed that Linc is very fond of.

For me, Avast was the cause of this error. I simply disabled the "active" scanner and without logging out or restarting, the App Store immediately updated properly.

Gotta love antivirus, and third-party software.

Thanks, @urabus; disabling the Web Shield in avast! Preferences solved the problem.

I'm still satisfied with avast! for now, even though it seems to disable Dropbox automatic syncing as well. There might be Network Prefs firewall settings that can fix either of these problems instead of disabling avast! or another antivirus app; haven't figgered it out yet. 🙂

(btw, I tried Kaspersky recently and it slowed my system to a wounded snail's crawl 😠)

Lol, and thank you for my new favorite "slow" analogy - "wounded snail," that's awesome.

FYI, Sophos is, IMO, the best, least intrusive and least resource demanding AV software. However, it always ends up hogging up "inactive" memory during scans, and some other occasions. I don't know if it's a "leak" or what the problem is but it's never been fixed.

Was getting the same error. In my case, it was because I had marked the Comodo root certificate as untrusted in Keychain. Wish Apple used a more reputable vendor...

Thanks so so much, that solved the problem. this has been driving me NUTS for months. g-d bless.

@MGSouth: Same issue, same solution, fully agree. Would be nice if there was a console warning or some hint to indicate this, never would have guessed.

"In my case, it was because I had marked the Comodo root certificate as untrusted in Keychain. Wish Apple used a more reputable vendor..."

You think Apple installed Comodo? Why do you think that?

BTW: Comodo has a reasonably good reputation in the Windows universe. You just do not use this in the Apple Universe....

Fix for Avast users to receive updates from Mac App Store:

1. Open Avast Preferences

2. If Preferences is Locked, click the lock to Unlock

3. Under the Shields tab, select Advanced next to Web Shield

4. Under Exclusions tab, add the following two servers that will prevent Web Shield from denying MAS updates:

swscan.apple.com (https)

swdist.apple.com (https)

Done! Lock the Preferences again.

Hope this helps 🙂

Everyone who has installed Avast in a mac: uninstall Avast completely, only problems: good in Windows, Bad in Mac.

I have the same problem after fresh install of Maverics 10.9.2. I tried to manually download-install the update 10.9.3 and it was succesful, but the problem still occurs.

I tried to boot in safe mode... no help, I did not install any third party software since the fresh install.

I also wanted to use

sudo codesign -f -s - /Applications/Utilities/Boot\ Camp\ Assistant.app/

... so new window with Install XCode appeared, but there was also an error, that it cannot be downloaded and installed.

I encountered the same error while attempting to update a brand new iMac this morning.

After contacting Apple Support, I was told that the App store was brought down for unscheduled maintenance. This was not reflected on the Apple Status web page BTW. I was told to retry updating via the App Store in a few hours.

While some updates (iWork) did complete, the "error has occurred" message continue to display between updates. The other symptom was that my new iMac was not detecting that OS X 10.9 was in need of an update to 10.9.2.

Since you replied to CLcapital, I assume that you also have Kaspersky installed (?). Uninstall Kaspersky on your Mac, do not let it come back. Do not install any antivirus software.

BTW: Mavericks is at 10.9.3.

Nope. It's just having problems I guess. I have a 13" rMBP without Kaspersky installed and it's doing the same.