Can't update Airport Extreme

So far I have read about two different error messages.

1) The one I got was "-6721". The solution was simply to turn Wi-Fi OFF, then ON again. You can do this either via the menubar or the Wi-Fi settings in the Network preferences.

2) The other error I read was "-6753". If you scan down the list of topics for this evening, you'll see it listed as a topic. Their solution was to turn off everything then turn it all on again. That included their Airport device and their Mac. It can't hurt to try.

When these error show up after updating firmware, it strikes TERROR in my heart as I have seen so many botched firmware updates in my time that have bricked the routers. But that is NOT the case here, at least not from the errors reported so far.

In the worst case scenario, you can break out the manual for your Airport device and read about how to factory reset it. Manuals are available as PDFs via Apple's Support page. Once reset, you access the device again via Airport Utility and try the firmware update again. If the update simply will not take, no matter what, it's time to talk to Apple as you may have a busted device.

It is possible that the router is an older router.

open up your airport utility app in your utility folder. update the routers first, then it will let you update the actuall airport utility application. also after you update, if you feel you like some of the things in the older software, you can then download the older app back to your computer by going to http://www.apple.com/support/airport/

Like Derek mentioned, I got error 6721 when updating one of my Airport Express. I have two running upstairs with a base station downstairs. The base station and the express I use for airplay updated fine, but the express I use to extend the wi-fi was giving the error when trying to update. It remained green but it wouldn't update.

Derek's advice to turn the wi-fi off and on again ended up being the solution that worked - though no initially. After I turned it off/on, the express turned amber on the unit and it wasn't even showing in the utility, which was asking me if the unit was still in range of the network (which it was). So there was no opportunity to update the express in the utility, as it was grayed out. After simply unplugging the express and plugging back into the wall, everything went back to normal - green and updated.

Thank you. Turning WiFi off worked!