Unable to access External Drives and Disk Utility after updating to macOS Sonoma.

this has been incredibly frustating to me too! I have a samsung T7 SSD and noticed that my mac would not reliably read it after upgrading to sonoma software. I couldn't think of any other changes, but did not suspect that a software upgrade would have caused this problem. After reading several forums, I am shocked that this is a common issue from a macOS software UPGRADE. it's embarassing that apple pushed an upgrade that created problems rather than solving them.

Nowadays, I just plug in my ssd and wait 30-40 minutes for it to randomly show up on my homescreen...

the same drive is immediately recognized by windows systems.

I believe problem with the data indexing algorithm, when you plug-in the device. If you have an empty storage, you will see all your disks almost immediately. But if you have big storage and big amount of files the drive will not be mounted until everything got indexed.

From this point I believe Apple Sonoma OS developers should look at the mounting strategy and do all indexing works in background, not on the moment of mounting the disks.

For those who has a lot of files and if they are big - be patient and wait until everything appear, once you have plugged-in. Otherwise you will lost your data.

My Apple M3 Sonoma 14.2 is only two months old.

I'm very lucky that I had copied out my photos (I'm a photographer) before my SD card files were deleted or became unreadable. I don't remember exactly what happened, but suddenly the card couldn't be read and all the files were gone, even my Canon camera couldn't access them.

I don't recall the exact error message I received after the files were deleted or became unreadable.

Now, I'm hesitant to find a way to connect my old 1TB external hard drive because I'm afraid a similar issue might occur, causing me to lose all my old files. This external hard drive cannot be read now ...

Am I missing a step somewhere?

I think you are missing all of them: Create a bootable installer - Apple Support

Once the installer downloads, it will try to run, but you can't install an older version over the top of a newer. Quit the installer and follow the steps to create a bootable installer.

Glad to hear you figured things out. I wish Apple would say something to warn people.

What looser at the Apple company is responsible for this mess up?

Do we all have to change to microsoft to continue?

Also, Apple started to remove negative comments on this thread. At least they are aware of the issues.

feketegy wrote:

Also, Apple started to remove negative comments on this thread. At least they are aware of the issues.

The moderators aren’t software engineers.

Exactly, and I mean really EXACTLY same behavior, I'm using windows to "fix" external drives to be used on mac again.. you wrote on 24 oct.. today is 14 Mar.. Thanks Apple.

No. It did not.

updated to 14.4.1 and it does not fix. I don't know what to do. I have 4 5T and I can't read any of them

I just purchased an M2 Mac Mini and Sonoma is causing these issues for me as well. Does anyone know if a fix will ever actually happen?

I can copy files to ExFat on my mounted drive BUT just not using Photos. It advises it can't find enough space. Then while doing this process the iphotos library used to create these files in the originals/masters folders so I could access them via a file path in windows, no biggie. But now I realise that has changed I think some time ago and I'm spending the day exporting my photos library.

The Photos Library must be on a Mac formatted drive. It uses features other file systems do not provide.

While the path is different, you can still get to them from Finder.

A powered USB hub seems to be a good solution. On my 2021 iMac I've been successful using the more highly powered usb connector on the back of the computer. Try different ports if you can.

It did not. I really can't believe Apple has let this go for so long. Very ironic that it keeps reminding me I haven't done a backup in x many days.....