Q: Update to Mountain Lion 10.8.5 has killed my wifi access. Help needed.

Renew DHCP Lease was a temporary fix for me, wifi went away again after the next restart. Deleting and re-adding Wifi Service on my Network Preferences didn't work at all. The problem seems to be in turning on the wifi card. My menu bar icon says it is on (but grayed out), but my Network Diagnostics says it is turned off. No issues whatsoever if I am booted from anything other than 10.8.5.

Still kicking myself for not backing up before the 10.8.5 upgrade, last time I'll ever make that mistake. In 25 years as a loyal Apple customer, this was never something I had to worry about, because it always just worked. I'm in a state of disbelief over this whole thing, and working on five lost days at this point. Thanks, Apple.

I've been attempting to downgrade to 10.8.4, as it still seems to be the only reliable fix on record. Is it normal to take 20 hours to download necessary components for a system install when booted in Recovery Mode? I've cancelled the process twice already because I don't have the time to spare. Let it run overnight the second time before giving up. Those who did downgrade, was it the same for you?

we all have the mess

the only consistent and simple thing that has worked for me ....  restart with power source disconnected ....

it must force the cycle into some kind of reset so it ignores the stupid stuff that came with 10.8.5 ... apple should be ashamed at the problem and more ashamed they have not put a fix out yet .... 

all the "solutions" have reports of working, and then not, so is that a solution or a way to kiss good-bye to many hours of time ....

there is always ethernet - but who's kidding who - that's not why we bought the gear

good luck to all ...

Have you tried shutting the machine down, disconneting power and then turning the machine on after 10 minutes ? Have you tried a SMC reset in case the above procedure did not work ?

I had the same issue with my late 2008 macbook.  I turned off bluetooth from the menu bar and then opened network preferences.  I removed blutooth and wifi from the left hand list and then applied the changes.  I rebooted the mac and then created the wifi connection again (I didn't do the bluetooth).  I have powered on my macbook at least 4 times and the wifi remains okay.

UPDATE: I finally found the fix that works for me, and still works (so far) even after multiple restarts!

I've seen many suggestions of removing the Wifi service from Network Preferences, and re-creating it. This fix, among all the others, did not work for me until I did it this  way:

First I deleted all services from Network Preferences, except Ethernet which I needed to connect to the internet.

Then I rebooted my Macbook in safe mode, then ran Mountain Lion installer again (I didn't do the recovery disk installer to downgrade, this one installed on top of the faulty 10.8.5).

First thing after Macbok restarted, I repaired disk permissions. Then I created a new Wifi service in my Network Preferences, and it actually did work, where it didn't before. Plus my wifi still works after a couple reboots; whereas any prior fix that did work, stopped working after a restart.

Just passing along my update, in case this fix might help anybody else who is as frustrated as I was.

Also, I saw a comment on this thread or another, that somebone was told from Apple support to NOT install the Airport update if they are having this issue. I have not done this, and I don't intend to.

Try Helloson's fix here: worked for me.

https://discussions.apple.com/thread/5305545?start=30&tstart=0

I have never experiecned such a thing!

This solved my problem. Thanks

Helloson's solution worked for me too (https://discussions.apple.com/thread/5305545?start=30&tstart=0). Annoyingly, it was very similar to what a few of us have been trying all along - the only difference is that you reboot your mac after removing the wifi connection, then add the connection again.

BTW - I'm using the same network card that other are reporting problems with:

Card Type:          AirPort Extreme  (0x14E4, 0x8D)

Firmware Version:          Broadcom BCM43xx 1.0

Same thing happened to me with a quircky twist.  I am new to MAC - got the 2008 in July 2009 for my daughter, and it got her through high school.  When she left for college last month we got her a new MACBOOK Pro, and I inherited the 2008 MACBOOK (I call it a hand me up).  It was running Snow Leopard, and updated to Mountain Lion two weeks ago and got the 10.8.5 version.  Every thing was fine - even turned it off an on again to make sure.  Then the next day when I turned it on WiFi was gone.  Spent hours with phone support (under 30 day OS upgrade support) - they finally gave up and suggested I go to an Apple Store - luckily I have one close by.  Had a great Genius Bar guy who tested the entire system - all hardware checked out OK.  So he said we should wipe the drive and reinstall the OS.  At that point, their servers had 10.8.3.  All was fine.  Before I left he said to make sure I update it with the latest version.  I was going to travel, and put it off a week.  Then ran the update, and exactly the same thing happened.  Fine on reboot, then WiFi gone the next day.  Back to the store.

Got the same guy and asked him to take me back to 10.8.3, which he was able to do.  Also, on his suggestion during the first visit, I bought an upgrade kit from Crucial to bring it from 2GB RAM to 4, and he installed that for me.  Now the machine is working just fine.  This is a trial run for me.  So far I love the MAC and intend to get an iMAC when they ship with Mavericks. 

From what I've read, it seems to be the Airport utility part of the upgrade.  Also some people said to check the battery, but mine was replaced about a year ago while it was still under extended warranty. I am not going to run any further updates to the OS until I know this has been resolved.

The fix provided by Helloson has stopped working for me. I need to repeat the fix after every reboot. Grrr!

Had same problem, just got solved after calling Apple Support, here's what worked =>

1. Shut down MacBook (13" Late 2008)

2. Boot into Safe Mode by holding SHIFT KEY & pressing POWER botton, (that'll clear Start Up cache)

3. hold SHIFT key down until bar appears bottom middle of screen (it'll take awhile)

4. when status bar/Dock/desk icons appear, check wifi (mine wifi connected immediately as had previous to 10.8.5 upgrade)

5. with wifi connected & MacBook in Safe Mode, Advisor had me open Safari & check several web pages, all worked

6. Shut down MacBook

7. Start up in normal mode (ie no keys to hold down)

8. WiFi back, everything works!

Hope this works for you too!

^ been there, tried that. It works durring the os install as well. Best of luck with next reboot.

I have upgraded my mac mini (late 2009) to OS  10.8.5 from snow leopard and now it finds 5 ghz network only! In 2.4 ghz range it seems to have a very very low sensitivity. Of course before the upgrading everything worked fine.

ditto that...   this is definitely a bug.

now I can't even get back to where I was....  I have to remove from networks, reboot and add back every time in order to get my wifi to work.  this is ridiculous!!!