“Invalid Password” when connecting to a Wi-Fi Protected Access network

About AirPort Client Update for MacBook and MacBook Pro

This update is recommended for some Intel-based Macintosh computers running Mac OS X v10.5.8 and addresses an issue with AirPort performance while running on battery power. It may only be installed on:

MacBook (13-inch, Late 2007)
MacBook (13-inch, Early 2008)
MacBook (13-inch, Late 2008)
MacBook Pro (15-inch, Early 2008)
MacBook Pro (17-inch, Early 2008)
MacBook Pro (17-inch, Late 2008)

All of sudden yesterday, I found that I couldn’t connect to my home wifi network from my MacBook running OS X v10.5.8. My home wifi network uses WPA2-PSK security.

The airport client kept asking me to re-enter my pass phrase, but each time it came back with “Invalid Password”. However, every other wifi device at home could connect ok. I even tried changing the pass phrase, deleting the network settings, and some other suggestions I found online – but nothing made any difference. I even changed the wifi channel (although, I’m almost sitting on top of the router and its by far the strongest signal despite 3 other competing networks nearby).

In the end I installed this update. I don’t think I was missing it in the first place as wifi has been working flawlessly with WPA for a while, but I imagine it may have reset something that was corrupted.