macOS is "Unable to Check for Updates" The hard drive on my iMac died &amp; I had it replaced.  They installed a new drive, wiped it clean &amp; re-installed the OS.  When I brought it home, I went through set up, pointed it at Time Machine, and viola! next memory my machine was up &amp; running.

With one catch...

I can't get any OS updates.  It keeps saying it's unable to check for updates, make sure you connected to the Internet.



I've tried rebooting a few times to no avail.  I can also connect to websites just fine, including apple.com.

Any suggestions of what to try?
Seems like the App Store may be having some problems today.

https://twitter.com/macrumors/status/1091369924847558658

https://www.apple.com/support/systemstatus/

I experienced the same problem on a Mac mini (2018) running macOS 10.14.2.

Based on the comment from JBis, using softwareupdate --list was useful to confirm that an issue exists.  

$ softwareupdate --list
Software Update Tool

Finding available software
The operation couldn’t be completed. (NSURLErrorDomain error -1012.)


On a MacBook Pro running macOS 10.12.6 (Sierra) I was getting similar behavior.  The difference on macOS Sierra was that the App Store Updates tab would generate a popup indicating that "An error has occurred", which also included the last line of text from the softwareupdate output.