iMAC 21" WIFI failing after 10.7.4 update

If I do this, will I lose all of my non-system files created/changed after the install of 10.7.4?

Replacing the IO80211Family kext with Kext Drop did NOT work for me (I followed all of the instructions carefully, including manually deleting 10.7.4's 420.3 kext in advance). My WiFi is still dropping and there's no way to turn it back on without rebooting.

So far the solutions I've tried to no avail:

• Replace kext with old version from 10.4.3

• PRAM & SMC reset

• Turned off bluetooth

• Tried it with a bunch of different Apple and non-Apple routers (makes no difference)

• Took it to a certified apple tech shop (said the hardware was fine so couldn't help me)

• Called apple tech support (useless)

• Both prayed to and cursed at the ghost of steve jobs

Has anyone else noticed that after the first reboot the WiFi menu comes back greyed out and says "No WiFi Hardware installed"? A few more reboots eventually I get it back. I'm surprised no one has mentioned the "No WiFI hardware" error here though. There are a few other threads, probably about the same bug, where this is the main symptom.

I'm on a Mid 2010 MacBook Pro rather than an iMac, but this is almost certainly the same issue. Everything worked great until the 10.7.4 upgrade.

P.S.: I was watching the console while the wifi crapped out on me, and unfortunately nothing showed up. No errors, nothing. Also no errors wen I try to turn wifi on and off (it doesn't turn on, just stays off).

However, when I tried deleting the WiFi interface and then added it back in, here's what I saw in the log:

12-07-07 1:13:22.221 PM configd: bootp_session_transmit: bpf_write(en1) failed: Network is down (50)

12-07-07 1:13:22.221 PM configd: DHCP en1: INIT transmit failed

12-07-07 1:13:22.226 PM UserEventAgent: CaptiveNetworkSupport:CaptivePublishState:1211 en1 - PreProbe

12-07-07 1:13:22.228 PM configd: network configuration changed.

12-07-07 1:13:23.000 PM kernel: WLAN adapter PCIE config space was not restored (stateNumber = 1)

12-07-07 1:13:23.000 PM kernel: wl: syncPowerState called when card is down.

12-07-07 1:13:23.000 PM kernel: WLAN adapter PCIE config space was not restored (stateNumber = 2)

12-07-07 1:13:23.000 PM kernel: wl: enable called when card is down.

12-07-07 1:15:22.130 PM SCHelper: active (but IDLE) sessions

12-07-07 1:15:22.130 PM SCHelper: 0x10410a3d0 {port = 0x2c0b, caller = System Preferen(316):com.apple.preference.network, path = /Library/Preferences/SystemConfiguration/preferences.plist}

12-07-07 1:15:22.130 PM SCHelper: 0x7fcf2c800dd0 {port = 0x2113, caller = System Preferen(316):com.apple.preference.network, path = /Library/Preferences/SystemConfiguration/preferences.plist}

(It did't work by the way)

Didn't work for me either. I have an older iMac than many report having the wifi drop problem with. Most seem to be 2011, mine is a 2010. Don't want to repeat what you may already know. But what worked for me was changing from WPA to WPA2. Don't consider that a permanent fix and look forward to Apple issuing an update that addresses this problem.

Well I finally caved in and did a full system reinstall (reboot while holding Command + R, then follow on-screen instructions). This seems to have fixed my problem — 1+ hour now without losing WiFi — and turned out to be a lot less painful than I expected. After the reinstall the system basically came back without anything lost. All of my files and settings are exactly as they were before, except my WiFi is working now.

There's still a chance it will crap out, but this is the longest I've gone without it dying since I upgraded (or should I say "upgraded") to 10.7.4.

... aaaand I spoke to soon. WiFi crapped out again. Pretty much out of options now, other than trying to restore from an old 10.7.3 backup.

Using WPA instead of WPA2 isn't a solution for me since this is happening on a MacBook which often connects to WiFi networks that I don't control (like the one at the coffee shop I'm at right now).

I'll call Apple again on monday and pester them until I get some sort of solution. Pretty sure they're pushing a faulty OS upgrade and refusing to own up to it.

This Apple engineer contacted me and possibly others in this forum about a month ago regarding the wifi drops, an issue he was working on -- Suresh Balachandran <sb@apple.com>

I ran some reports for him and he seemed interested in finding a solution.

A few months ago I suddenly have had a lot of kernel panics (I believe it was directly after installing 10.7.3) - first suspicion was hardware and of course especially the ram. After trying a lot of things I gave the iMac 21,5" mid 2011 to my local apple shop. They ran all their tests and couldn't find a hardware problem.

With this iMac it was the first time I completely installed lion from the ground because getting rid of the old stuff that was collected over the years with all my old macs - unfortunately I haven't had any problems with the previous machines.

Soon I found the problem - it was the wifi - I connected the iMac by Ethernet and since then I haven't had any kernel panics!!!

But these days, looking forward to mountain lion, I tried it again by wifi and I have exactly the same problem like many others, iMac wifi is working (no panics and a stable connection) - going to sleep - wake up and I am not able to select any wifi connections! It is searching again and again... No networks available. Please apple fix this bug - 10.7.4 didn't fix that - I am hoping for 10.8...

Does anyone here use bugreport.apple.com or http://www.apple.com/feedback/macosx.html ?Here is the user's community,not bug report place

Like others, I have tried several things and all eventually fail and drop the connection.

However, what has reduced the pain is that I turned on the 5Ghz connection of my Apple Airport and told the iMac to connect with 5Ghz. Now, it will still drop the connection, but unlike the 2.4Ghz connection, using 5Ghz, the iMac will allow me to just turn off the wifi, then when I turn it back on, it will reconnect without having to reboot.

The problem is still a pain in the butt, but at least I do not have to reboot now.

Duffy

Sure I did... Isn't it called a discussion?

my machine (2011 iMac, 10.7.4) has been free of intermittent wi-fi problems since changing the 2.4 GHz channel to 1 on June 20th.......although, logically, this should have no effect, since the problem seemed to be a total inability to see 'any' wi-fi hotspots, it has worked........try it!

I also tried that. It was one of the suggestions I found when researching this problem. It worked for two weeks, then a drop which required a reboot.

That's when I decided to try the 5Ghz connection. It still drops, but at least to reconnect, I just turn off wifi on the computer then turn it back on and it reconnects. Issue still there with the drop, but at least I do not have to reboot.

I suspect the issue is still there, we just get fooled into thinking something will work because it does not drop as much as it did it the past after we tried something.

Apple obviously hosed up something in a update, they just have to figure it out and then fix it. I'm hoping the new release of OSX will do just that.

Duffy

So my MacBook is back at the shop. It may have been a hardware problem after all. They're going to replace the AirPort card and see if that does it.

I tried rolling back to 10.7.3 from a Time Machine backup, but the WiFi was still failing. I also did a clean wipe of my system and reinstall from scratch, but WiFi was still intermittently going down.

The fact that my problems started the day I updated to 10.7.4 might have been a coincidence, but I still wonder if something about the upgrade hosed my AirPort...

Guys,which MCS index do you have?

to see it - hold option key(alt) and click the wifi bar