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I just got this 1TB SSD, and an external enclosure which I'm hoping to use as a sound libraries disc.

I started moving stuff over to it, and ran into some issues. I started getting Error -50 when trying to copy files to it.

I tried to run First Aid, but it failed as it could not unmount the disc. It said that some files were in use. I force-ejected and ran First Aid which showed it was OK. I don't see how to repair permissions in El Cap's Disk Utility. I recall I may need to do this from terminal.

I still can't copy files to it because of the -50 error.

I'm running OS 10.11.6 El Capitan, and formatted the SSD Extended Journaling, GUID Partition Map.

I tried searching solutions but it was kind of all over the place.

You need to do the Google. Yes, the Google you must!

http://osxdaily.com/2015/11/04/verify-r ... -mac-os-x/

Did you format the drive or are you using it as is? I'd START by formatting/partitioning it on my machine.

Ha. I googled "mac "-50" error code" and got about a dozen boiler room scam sites offering to fix the problem for a toll call. Other than "user parameter error", there really isn't much useful information.

Mac error codes:
http://www.cs.cmu.edu/afs/cs/user/lenzo ... rrors.html

Settings are correct as long as you didn’t select any of the security settings. If you selected Write to Zeros, that’s the mistake you made because your SSD is now full. If so, Reformat. Do a Safe Boot to force Garbage Collection into action, then reboot normally. Leave running overnight. You should be fine in the morning. Garbage Collection with TRIM takes about 24 hours to completely clean up a full 2TB SSD so 8–12 should be fine on a 1TB (TRIM doesn’t function over USB but GC is built into the SSD).

Otherwise. I run into this problem now and then as recently as two days ago when I suffered a power outage while installing a TB dock. Wiped out both my 2TB SSDs and made it a PIA to bring back to life—but I was able to.

Reboot. Run Disk Utility.

When it shows up in Disk Utility, you’ll see the Drive and below that, the Volume.

Erase the Drive (not the Volume) if you can—the name you select will be applied to the Volume. This should do it and the Volume should mount.

Next, run Get Info on the mounted volume, scroll to the bottom. Ignore Ownership on this drive should be checked but greyed out. If not checked, click on the padlock to unlock, check the box and re-lock.

It should now work.

If not, run Repair on the Drive first, then the Volume. If it won’t repair the volume, erase again as above. If both are ok, do a Safe Boot, then normal reboot and let run overnight.

If either D or V won’t Repair, reformat as ExFAT GUID. Copy a file over. If that works, reformat Extended Journaling again.


If it was a pair of APFS externals that went South, I’d say to format ExFAT, then Extended, leave connected overnight so that Garbage Collection could do its thing, then reformat APFS.

On my old iMac, I had my external SSD connected via eSATA. Enabling TRIM on the internal automatically extended it to the external. Connected via Thunderbolt, SATA externals don’t support TRIM until sudo trimforce enable is run in Terminal. I don’t know that is true with NVMe 3 x4 externals connected via TB3 or just SATA III. I’ll post more completely on this later.

Thanks all. Thanks, Mike Halloran for the detailed steps!! I truly appreciate it!!

mikehalloran wrote:Settings are correct as long as you didn’t select any of the security settings. If you selected Write to Zeros, that’s the mistake you made because your SSD is now full.

I did format the drive first, but didn't do any special security stuff. Just the standard quick erase/format.

mikehalloran wrote: If so, Reformat. Do a Safe Boot to force Garbage Collection into action, then reboot normally.

So Garbage Collection will just take place as part of Safe Boot?

I'll follow all of these instructions -- hopefully this evening & tomorrow.

So Garbage Collection will just take place as part of Safe Boot?

It's weird since GC is part of the SSD, not OS like TRIM.

Something about a Safe Boot tells the drive that it's ok to run Garbage Collection sooner rather than later. As long as file transfers work, it's not going to be a problem and it will all work out over time. But if you plan to do large file transfers after a problem, you want to give an SSD some time to clean up, so to speak.

None of this will affect normal operation.

Used to be (and may still be) that if you run Disc Utility>Repair Disc on an SSD that is not your boot drive, it will be trimmed as part of the process.

I did boot in safe mode. The drive did seem to be working. I tried deleting some files, it sent them to the trash (which it gave errors for before), but then it was taking a really long time to empty the trash. After a couple of hours I hit the X to stop emptying the trash. It's been "stopping" for a couple hours now.

Perhaps the drive is busy doing the Garbage Collection thing.

I was wondering why it kept saying "Files in use" (when it refused to unmount or eject). Is it possible that has to do with that Spotlight thing- where it scans the disc for a Spotlight index?

Anyway, I will still go through the steps tomorrow, but I'll just let it "stop emptying" trash while I sleep.

The SSD is now working as it should.

It is possible that some of these errors were coming from a source drive (rather than the SSD which was the destination). There are some old system back ups, and for some reason they are showing up on the drive itself, whether in the trash or not. They are "in use" and cannot be deleted. I tried to remove from terminal, and as far as terminal is concerned the files down exist. I tried renaming them, and that did not help. Right now they just look like empty folders.

I tried using Drive Genius to scan for "active files" but that turned up empty. There's a lot of data on this drive (over a TB) so I'd rather not try to move it off and reformat, but I will if that's the required action.

I think the culprit was the 4 TB spinner and not the new SSD. Though it may have been both.

There was some glitch that First Aid didn't catch, nor did Drive Genius. A few stubborn, apparently empty nested directories that would give error -50 and say they were "being used". There was no way to delete them. I even got the latest version of Drive Genius which is supposed to help show "active files" and allow you to delete them. Didn't work.

Ultimately, for that drive, I had to copy everything off of it, and reformat.

I think everything is good now. Glad to have everything backed up, and moving the sound libraries off my root/startup SSD (on my RMBP) has freed up some space.

Thanks again for the help.

stubbsonic wrote:and say they were "being used"

I'm seeing this one more and more in newer versions of OS X. Almost every time I try to delete a large number of files, I'm told some files are in use, when clearly they aren't, at least not by me. Maybe someone in Moscow or Menlo Park needs them. I'm also seeing files with a "locked" status that I didn't lock, and these sometimes result in the message that they are being used. Under the "doesn't know its $^&@ from its elbow" heading, you'll get this message if the Finder tries to delete a file that is already queued for deletion.

HCMarkus wrote:Used to be (and may still be) that if you run Disc Utility>Repair Disc on an SSD that is not your boot drive, it will be trimmed as part of the process.

Not over USB since USB never supported TRIM on a Mac. It's Apple, not the spec since Linux can support this.

SATA external in a Thunderbolt housing or dock no longer automatically supports TRIM either. Weird considering that TRIM is automatically enabled on the boot drive if an NVMe SSD. Again, an Apple decision. This restriction is defeated by running sudo trimforce enable in Terminal. I don't know when this occurred—OS 10.11/12/13?. Still true in Mojave and I was surprised to learn it.

The new CYA message begins with, IMPORTANT NOTICE: This tool force-enables TRIM for all relevant attached devices, even though such devices may not have been validated for data integrity while using TRIM... and continues.

Interestingly, if booting from an NVMe blade over TB3 such as the Samsung X5, the OS thinks you're booting from an Apple internal. TRIM support is automatically enabled. I understand this may be true of the X5 when used as storage only but can't confirm it.