Suddenly Can't Drag File Folders to Hard Drive or Backup Drive (Error code -36)

Researchers did a really big study of rotating magnetic drives in google server farms. One of the many conclusions they reached was that drives that start to develop bad blocks often continue to go very bad, and over a very large sample they often become unusably bad in a period as short as a few months. Your drive could be going bad even more quickly than average, or could already be bad but you just don't know it yet.

SSD drives will fail in similar, but not quite identical ways.

You should consider Erasing and re-imaging that drive, to make certain it has all good data on it. Be prepared for the possibility that initialization fails with 'too many bad blocks'.

In Disk Utility>View, select Show all Devices, highlight the top left entry.

Run Disk First Aid on all items in the left panel, from top down.

You can use Drive DX to possibly get a better view of Drive health…

https://binaryfruit.com/drivedx

Are you running any VPN, Anti-Virus, or Cleaning apps?

We need to see what all is running, a report from this will not display any personal info...

Using EtreCheck - Apple Community

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info. Give it Full Disk Access.

https://www.etrecheck.com/

Give etrecheck Full Disk Access before running.

Thanks for Old Toad’s etrecheck instructions…

Slow iMac 2017 - Apple Community

I found the same issue and got the same error (on Ventura 13.6.9). I couldn’t copy a folder with jpg's from one external drive to another external drive. However, I could copy the folder to the desktop of the drive that came with my iMac — and then without any trouble could open the pic in the jpg identified in the error. This doesn’t seem possible given Grant’s explanation above. Perhaps there is another explanation. Any help would be appreciated!!

Error: "The Finder can’t complete the operation because some data in “DSC_0352.JPG” can’t be read or written.

(Error code -36)

<< I use BitDefender as anti-virus. >>

that is complete nonsense. You should completely un-install that scare-ware.

MacOS shares a lot of the lock-down mechanisms developed for the iPhone. Applications are all sand-boxed with a list of the resources they require, and they cannot ask for anything outside their sandbox without crashing. Signed Applications are checked that they are from legitimate Developers, and Notarized Applications are delivered with the assurance that they have NOT been modified since their release by the Developer.

Recent versions of MacOS completely changed how you should think about malware.

From MacOS 10.15 Catalina onward, the system is on a Separate, crypto-locked System Volume, which is not writeable using ordinary means. Any unauthorized differences that appear to the crypto-locked volume are quickly detected and you are alerted.

So you could store just about every malware known to mankind on your Mac, and your Mac would not get infected spontaneously. Scanning for virus-like patterns might make you feel a little better now, but it is outdated nonsense.

Nothing can become Executable Unless/Until you supply your Admin password to "make it so".

By far the easiest way to cause poor performance, instability, overheating and crashing is to install ANY third-party speeder-uppers, Cleaners, Optimizers, or Virus scanners, Bit Torrent, or a VPN that you installed yourself. 

Try removing those things, and if you experience improves, we can make another check mark next to that fixing problems for thousands of users.

if you continue to see error -36, then you may have actual Bad blocks on the source drive.

DriveDx can tell you about that.

I ran the Disk Utility’s First Aid. It works now! Thanks!

macerror -36

Mac OS error -36 (ioErr): I/O error (bummers)

I/O error sounds generic, but is actually VERY specific. it says that one or more data blocks in a file was not readable, even after being re-read using error correction 1,000 times.

The information in those data block(s), and therefore the contents of that entire file, are unknowable, and unless you have a Trusted Backup copy, those file(s) are lost.

<< Error: "The Finder can’t complete the operation because some data in “DSC_0352.JPG” can’t be read or written. (Error code -36) >>

Mac error -36 is unbiguously I/O error.

But the reason for re-reading as many as 1,000 times is ... sometimes when we try again, we get lucky and get good data.

So when you tried to copy that file again, and it re-tried again, you got unbelievably LUCKY and it went through before the re-tries got to 1,000 and it gave up.