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If you’ve ever tried to transfer a file to or from your Mac and were greeted with the mysterious Error Code -1309, you’re not alone. This code can be both confusing and frustrating, especially if you’re unsure what’s causing it. But don’t worry—once you understand what Error Code 1309 means and how it arises, the solution becomes much clearer.
Error Code 1309 is a fairly common Mac issue that usually pops up when trying to copy or move a file from a macOS system to an external drive, or vice versa. The good news? It’s less of a Mac problem and more of a file system compatibility issue.
What Is Error Code 1309?
Error Code -1309 typically signals that macOS is attempting to move a file that exceeds the file size limitations imposed by the external drive’s formatting system—most commonly, the FAT32 file system.
FAT32 (File Allocation Table 32) is an older file system that is widely supported across different operating systems including macOS, Windows, and Linux. However, one major drawback is its limitation on file size. FAT32 cannot handle a single file larger than 4GB. This is where Error Code 1309 usually rears its head.
Common Scenarios That Trigger Error Code 1309
Here are a few typical situations where you might encounter this error:
- Transferring large video files (over 4GB) to a USB flash drive formatted in FAT32.
- Backing up high-resolution images or software packages to an external hard drive.
- Moving game data or disk images that exceed the FAT32 file size limit.
In each of these cases, the issue is not with the Mac itself, but with the file system of the destination or source drive.
How to Fix It
There are several ways to tackle Error Code 1309, depending on your circumstances.
1. Check File Sizes
First, identify if file size is the culprit. Highlight the file in Finder and press Command + I to open the Info panel. If the file is larger than 4GB, and the drive is FAT32, then the file system is to blame.
2. Reformat the Drive
If you often need to transfer large files, consider reformatting your external drive to a file system that supports larger file sizes:
- exFAT: This is a modern replacement for FAT32. It has no realistic file size limits and is compatible with both Mac and Windows.
- APFS or Mac OS Extended (Journaled): Ideal if the drive will be used solely on Mac systems.
To reformat a drive:
- Open Disk Utility.
- Select the external drive from the sidebar.
- Click Erase, choose a format like exFAT or APFS, and proceed.
Note: Reformatting will erase all data on the drive, so make sure to back up important files first.
3. Split the File
If reformatting the drive is not an option, consider breaking the large file into smaller chunks. You can use apps like Split&Concat or even native Terminal commands for this task. Once transferred, you can reassemble the parts on the destination system.
4. Use Cloud Storage
Another practical workaround is to upload large files to cloud storage services like iCloud, Google Drive, or Dropbox. You can then download them to the target device without worrying about file system limitations.
Final Thoughts
Error Code 1309 may seem alarming at first, but it’s relatively easy to resolve once you know what’s causing it. Simply put, the error is a result of trying to move a file that’s too large for the FAT32 system to handle. Whether you choose to reformat your drive, split the file, or switch to cloud storage, there’s a solution for every situation.
Understanding how Mac file systems interact with external storage formats can save you a lot of stress down the line. So the next time you bump into this error, you’ll know exactly what to do—and more importantly, why it’s happening.