Crucial X9 SSD not showing up after update to Sonoma 14.3.1 - MacBook Air M2

Had the issue as well this morning. Tried all of the suggestions here, nothing worked.

Connected to a PC, was detected as having errors so I selected "Fix and Repair" on Windows 11. After that connected to my M1 Max Mac with Sonoma 14.6.1 and it is again recognized and working.

Update this morning - 1_ its definitely not teh crucial ssd as it works on other devices i tried, 2_ the person who suggested opening safari is a genius, not sure how or why, as i use another browser as my default, but i opened safari, navigated to a single page, then mounted one of the ssd drives and bingo, found it and can read it....how weird!! by the way i also couldnt attach my iphone to synch with itunes and update software for some recently downloaded media, but i will leave that for later but as it it linking via usb-c ports to M3 macbook pro i suspect its teh same post sonoma issue, but am happy today with the ssd "success" for now....hope this also helps one or two of you...

I found to my great relief my x9 was opened no problem on my old laptop that hadn’t been updated. Then back to my newer MacBook and there it was again! Has worked perfectly since. So try that . I’ll put the kettle on.

Try another computer

Use the Crucial drives with the USB-C 3.2 Gen 2 cables that ship with them. Connect them directly to your M2 Mac USB-C port, not through a hub. The drives are pre-formatted as exFAT and to realize best performance with Sonoma, should be formatted APFS. You also have either a 3 or 5 year drive warranty, and if you purchased them directly from Crucial, you may be able to return for a refund or replacement.

I use Crucial X8 2TB drives here formatted as APFS and exclusively for Time Machine or as a drive for Parallels's guests. Been using these Crucial drives without issue for 2+ years.

I am using my Crucial X8 on macOS versions : 14.3.1, 13.6.4, 12.7.3 , and 11.7.10 without issues. If your mounting problems are restricted to the relative new X9 product, I would check with Crucial to see if they have a firmware update for it, or can offer any other suggestions for your circumstances.

I have the same issue, and it started after a re-boot a few days ago, I have 3 crucial ssd drives and 2 won't mount now (even though the 2nd one did Saturday), when re attaching for 2nd time, its a "computer says no" and i cant believe 2 drives of different age would fail., so must be something switched or an issue with software. same lights as above, so power ok, and i thought no moving parts in ssd so am guessing its software. Disk Utility wont run first aid and cant mount them either. On Sonoma 14.4.1 I hope this can be fixed soon?

Me to.

My Crucial X10 Pro will not mount on my Studio.

And attempting to format in APFS with Disk Utility causes rejection.

It did however mount as Ex FAT, even copied small files ( 25mb photos ) but if tried to

copy a large file of 915mb such as an MP4 movie ( Chose Psycho as seemed appropriate ),

it did a Mr Bates and Ejected from Desktop.

Further attempts to erase/format unsuccessful.

Interestingly , my other 2TB Sandisk SSD's are humming along.

So far not impressed with response/suggestions from Crucial.

Luckily I had just backed up ( updated the backup) to the old fashioned WD 6TB drive the night before (my System Photos Library 1.3 TB was on the Crucial ) and thankfully also on a older Sandisk 2TB SSD.

I'm adding my drive to the list - Crucial X9 SSD 4TB that seems to only appear when it pleases, and also randomly unmounts itself. Data seemingly unaffected. This is a brand new drive. My Macbook doesn't have USB C ports so I assumed the fact I'm using other cables could be part of the issue, but the symptoms seem identical to others described by users here. Will be keeping an eye on the thread for a fix!

Same here, literally started the second after I updated macOS to 14.5. First time I could fix it with first aid.. in Disk Utility but now it fails even that.

Crucial X9 4TB.

Any new developments on this issue? my Crucial X9 pro 4TB started disconnecting itself a few times for a couple days connected to my Mac Studio, I'm using the factory cable and its formatted as APFS in Sonoma, now it decided not to mount at all. any updates on this issue?

Yes weirdly I have an x6 and and x9. The x6 gets recgnised (it's just for time machine backups) but the x9 is nowhere to be seen despite having all my iMovie stuff on there as I'm using it as my working drive for iMovie to save filling up yet another laptop. I've swapped cables and various ports but no sign of the Crucial x9. I think I'll need to just send it back and see what they can do. It's not as if they're cheap so you expect them to work. I'll try another brand next time.

My x9 still had not been recognised by my MacBook even after being left on all night. I swapped it around and still no joy. BUT I clicked Safari (I was about come here again to comment) and maybe it was s coincidence but the x9 has appeared on the desktop and opened when clicked! I’m almost frightened to unplug the little b&gger.

I'm having a similar issue. Using a Crucial X9 Pro on an M3 MacBook Air running Mac OS Sonoma 14.5. Just purchased this hard drive 2 days ago and transferred a huge amount of irreplaceable files to it. Today it started popping up input/output error messages. I ejected it and reconnected it and now it won't mount. Disk Utility is showing it, but it's grayed out. I'm keeping my fingers crossed that someone has some sort of solution for this, because I'd be devastated if I lost some of these files.