When trying to update from iOS 5.1 I keep getting an error message reading "unable to check for update, an error occurred while checking for a software update". The update screen loads for a couple of minutes before showing this.

How can I upgrade to iOS 5.1?

  • 1
    Are you using the Settings app, or iTunes?
    – Tuesday
    Mar 10, 2012 at 2:33

1 Answer 1


It turns out you might need to set your DNS server to as I found out Here.

To change DNS settings, go to the Settings app and then pick Wi Fi in the left column. Tap the blue arrow that's on the right of your Wi Fi network name, and DNS should be an option, and you'll see a number like Tap this number and change it to be

Try the update after changing the DNS setting (wait a minute as you'll have to reconnect your wireless connection) and the update should work now.

  • 1
    That is doubtful. It's more likely that changing your DNS servers just refreshed your DNS cache. Something, which can be done by running the following command in Terminal: dscacheutil -flushcache It may be your ISP has some aggressive caching, but I doubt you'd have to migrate over to Google's servers (which incidentally are and
    – user10355
    Mar 10, 2012 at 9:54

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