Update: Good news! I am now able to get onto the 5GHz SSIDs. What changed? I rebooted my router, and it now seems OK.

So I may have cried Wolf about this problem, and incorrectly blamed Mavericks. The problem seems to have gone away after the router reboot. Whew! I still don’t know why I got the message that the previous connection was “open” not wpa2-personal. But I’ll take it.

Original posting follows:

I upgraded my 2.3GHz MacBook Pro to Mavericks yesterday, and had trouble with Wifi on 5Ghz. I’m using a Netgear WNDR3800 using the CeroWrt firmware. It had previously worked great on both the 2.4 and 5 GHz channels for this computer, and the others in my house.

After the installation, I selected one of the 5GHz SSIDs, and got the message, “‘CEROwrt-guest5’ was previously joined as Open, not WPA2 Personal.”

That’s not correct – up until the upgrade, that SSID had definitely been WPA2-Personal. So after casting about (turning Wifi on/off, etc). I finally went to the System Preferences and removed the SSID by clicking the “-” button from the Wifi-Advanced settings.

But this doesn’t seem to have solved the problem: Now I see a message, “The Wi-Fi network ‘Cerowrt-guest5’ could not be joined.” when I select that SSID from the Wi-Fi menu.

So I’m stuck. 2.4GHz works fine (both on an open SSID, and one with WPA2-Personal), but I have not been able to make 5GHz work. No workarounds yet, and a quick scan of Apple’s forums don’t have any indication of a fix.

See Update above – things are working fine after rebooting my router.