Compact flash cards stopped mounting to Imac and macbook pro. I have tried both a reader and directly from the camera.

Bet you're right about this. I've done every test and configuration and reset and still unable to read a CF card. It says the media is unreadable. SD cards work fine.

For fun, I'll try a Windows computer and tell ya what happens.

Eddie

Both my iMac and MBA until ten minutes ago were not recognizing CF cards. Sd cards worked normally in both external readers and the internal on the iMac. Now both work normally - I can upload CFs. Now all is normal. I'm baffled.

Eddie

I forgot to mention that may card readers work normally on my Windows computer too, if that matters.

So I am having this issue as well on a 2010 27" iMac
I have a GE Memory Card Reader that worked perfectly with 10.6 and now doesn't mount at all in Mountain Lion.

What good are these support forums if nobody ever responds to the issues?
There's NO FIX for this? I'm a photographer and I need to get my images.

Well there may have been an issue with the old card reader I was using. It worked, then stopped working. It's been a while but between then and now there was some sort of update to the OS. I'm sorry I can't remember exactly what that was but there was no indication that the update was for cards and readers.

The reader I was using was real cheap and flimsy and I figured I'd better get a new one so I went to the camera store and got a high quality USB 3 reader for SD and CF cards. Now all is well. It's a Hoodman Steel UDMA reader. Oh, I went to the office store first and found a reader (iHome, I believe) and it failed almost immediately - you couldn't get the dard into the slot). The Hoodman is like heavy duty metal cased.

Things are ok now but I'm sorry I can't say specifically what happened just that a new reader, at the time, fixed the issue.

Hello, encountereing the same problem in my imac mid 2011 21 inch. I've even tried making a new user and trying from threre, but its the same. Only thing thats remaining is the clean install option. But thats time consuming and since I'm a bit busy, I cant do it immediately. I'll post its result when I do it.

For now the only solution that works for me is accessing the sd card from Windows 8 running in Parallels. But thats not the way its supposed to work.

Meanwhile here is the feedback i left to Apple.

Hi,

Ever since updating to Mavericks, I can no longer format cards in the sd card slot. I've tried sd, micro sd with adapters, and capacities of 4, 8 and 16 Gb. In most cards i can read the contents, e.g. photos etc. In some (4 Gb one) I can even delete stuff and make folders - i.e modify contents, but in all the cases i'm unable to format. I've tried the following methods-

1.Disk Utility

2.Terminal

3.Apps

In all the cases I've failed.

I've even tested the cards in other devices (including Raspberry PI, Digital Camera, Mobile phones and 2 windows laptops- a sony and dell). They work fine there.

I've also cleaned the slot by blowing air, tried various methods like slightly removing card, inserting with a little pressure, restarted with the cards inside but its the same.

This happened to our office yesterday (Oct. 7, 2014). In the middle of downloading a recent photo shoot's images from a compact flash card --- the same ones we've used for a year, on the same card reader we've always used---suddenly the reader icon disappears from the desktop on its own, we get an alert that a disk was ejected improperly, and the iMac (27", 2012, Mac OS X 10.9.4) ceases to recognize CF cards or the reader. We moved to another Mac in the office where we've used he same equipment for months (iMac, 27", 2013, Max OS X 10.9.5) and same non-response. We tried another iMac (iMac, 27", 2012, Max OS X 10.9.5) and the same non-response. We put it on a Mac Pro (2012, Mac OS X 10.9.5) and the same non-response. And a MacBook (2010, Mac OS X 10.9.5) and the same non-response.

Before you comment, yes, we did switch out card readers for an alternate one, including the connector cable with the same non-response. We also tried several different CF cards. We sent an intern off to buy a new card reader and when that was connected we got the same non-response from all machines. We even reset PRAM. The kicker is that what was working fine for months and even years without a problem suddenly as of yesterday ceased to function. It effectively shut down our office for the day -- we're a graphics design firm and deal with hundreds of professional Nikon D3, D4 camera image downloads from our CF cards a day. We finally tried an older MacBook Pro (2010, Mac OS X 10.7.4) and we were able to bring up the images. We quickly downloaded them to an external hard drive so we could access them from our workstation Mac Pro and iMacs. We'll be buying a variety of different card readers today in an effort to find some sort of magic bullet fix.

But our feeling is that something in Mountain Lion has changed and created the SNAFU. It's a huge productivity obstacle in our business and we've now had to employ a Microsoft PC in order to bring up the very same CF cards(SanDisk and Lexar, 2GB, 4GB, 8GB, 16GB capacities) and card readers to access our photo image files allowing us to work. Something is wrong in the universe....can we anticipate a patch? Is anyone even aware? We don't appear to be the only ones but I'm perplexed that there seems to be only scattered postings here regarding this. We went from a thriving, bustling productive office to a screeching halt in the matter of 5 minutes. We worked through the problem for 2 hours only to arrive at a solution which put a dusty Microsoft PC in the hero's spotlight---simply by being able to read a CF card like every computer ought to. Yikes!

HI,

sorry to hear that! I was hoping my problem would be a unique one. I hope you got warranty as then you can get a replacement. unfortunately mine was out of warranty when this happened.

i've installed Yosemite and even this has not solved the problem. Looks like whatever caused it is hard coded into the firmware.

also can you tell me if you have any trouble with printers on your affected machines? My HP deskjet has stopped responding when connected to iMac. It works fine on a windows laptop

Has anyone seen where you've been able to upload from the CF but they are just like the top 1/16 of the photo and it just a bunch of digital lines? I've had this problem getting photos into iPhoto since Mountain lion. They import into windows just fine on my wife's laptop with the same USB reader.

Open iMovie then import then choose your camera,you can find your CF card's data there,this is the solution(when connection your camera with mac through camera's usb cable). This is the working and perfect solution.