While OS X is widely known considered to be a very user-friendly interface, its error messages can be a little…cryptic. A typical example is the Error Code -50. An error -50 is usually a parameter error and it occurs in the user’s parameter list.
More often than not, it occurs when you attempt to copy, delete, or move files from any external storage devices onto your machine. If you get this error message it probably means that you’re stuck with a file that you can’t copy/paste or even remove from your system.
But don't despair: there are some measures you can take to solve the error. Below are a few things you can try.
1. Rename the file
One of the easier ways to fix an Error Code -50 is to try simply renaming the file in question. This may help if you’re working with files that were created using Windows, as some characters in the filename that can be used in OS X are not allowed in Windows filenames. Choose any general name like “file1.txt” and confirm that you want to change the file extension. After that's done, try to move or delete the file using OS X Finder and the operation should successfully complete.
2. Unmount and re-mount your drive
Try ejecting your drive. Then unplug it, reboot your system, and plug the drive back in again. When it’s done the mounting, try moving the file. As simple and as obvious as it sounds, this trick will often work.
3. Diagnose your drive with Disk Utility
Disk Utility is a program included with OS X. You can run it for a variety of tasks, including creation, conversion, encryption, and compression of disk image files from a wide range of formats. It can also be run to check up on the integrity of your current hard disk or SSD - and that’s what we’re going to run it for.
First, make sure that the drive formatting is ready to go by running a verification routine with Disk Utility on the storage volume that contains the file that you’re trying to manage.
To do this, you must select the volume in question in Disk Utility’s sidebar, and then go to the First Aid tab and click on "Verify Disk". Any errors that show up will appear in red text. If any errors do show up, click on the "Repair" button to fix them. After that's done, you should be able to deal with the file without getting an error -50 message.
These are the easiest ways to solve error -50 messages. However, if none of these end up working for you, Apple’s support communities are rich in content and could always help you find more ways to resolve the error.