How to Fix Corrupted SD Card on Mac

SD card corruption is a common issue that can lead to unreadable files, system errors, or complete data loss. This guide will walk you through how to fix a corrupted SD card on a Mac and recover its contents. With specialized tools and built-in macOS utilities, you can quickly repair your SD card and restore your files. Our step-by-step guide will show you how to do it with ease.

Common Signs of SD Card Corruption on Mac

Corruption in an SD card can happen unexpectedly, leading to various issues that make your data inaccessible. Knowing what to look for can help you figure out if the card is corrupted before things get worse.

Below are the most common signs of SD card corruption:

• The most noticeable sign of SD card corruption is when your Mac no longer recognizes the card. It may fail to appear in Finder or Disk Utility, making it inaccessible.
• Corruption often leads to missing files or strange filenames. These could appear as random characters or symbols, making it impossible to open or view them.
• Frequent read and write errors also indicate a problem. Your Mac might fail to copy files to or from the SD card, or the card may refuse to save new data.
• Some files might display error messages when accessed, such as “the following disk images couldn’t be opened” or “This file is corrupted.”
• The SD card may become slow or unresponsive, freezing your Mac or the application trying to access it.

If any of these symptoms sound familiar, there’s a good chance your SD card is corrupted. To effectively prevent or fix SD card corruption, we also need to know what caused it in the first place. Let’s take a closer look at some of the most common causes of SD card corruption and how they can impact your data.

7 Common Causes of SD Card Corruption

While SD cards are quite reliable, several issues can lead to corruption, causing data loss or making the card unreadable. Here’s a detailed look at some common causes of SD card corruption.

• 💻 Improper ejection from the Mac. When an SD card is removed without being properly ejected, the ongoing read/write process gets interrupted, which can lead to file system damage. This interruption often causes metadata corruption, making the card unreadable or files inaccessible.
• ⚡ Power failures during data transfers. Sudden power losses, while your Mac is transferring data to or from the SD card, can damage its file system. This is especially problematic with SDHC and SDXC cards, where incomplete writes can corrupt large data blocks.
• 🔧 Physical damage. SD cards can suffer from physical damage if exposed to extreme temperatures, moisture, or shocks. SD cards, particularly those exposed to temperatures outside the operational range, can have warped memory cells, which lead to corruption.
• 🚫 Fake SD cards. Fake SD cards, often sold as high-capacity models but with much lower actual storage, are a frequent cause of corruption. These cards may appear to work fine until you exceed their real capacity, at which point data becomes corrupted.
• 📝 File system errors. Frequent use of the card or its use across multiple devices can lead to file system errors. This often happens due to the gradual fragmentation of data and errors in the FAT or exFAT structure, making files inaccessible or corrupt.
• 🦠 Viruses and malware. When an SD card is used across different devices, especially unprotected ones, it can pick up malware that modifies the file system. This can lead to data loss, making the card unreadable.
• 📉 Wear and tear on NAND memory sectors. All SD cards use NAND flash memory, which has a limited number of write cycles. Frequent writing and deleting gradually wear out the memory blocks, causing sectors to fail over time, which eventually leads to corruption.

Preliminary Steps to Fix Unreadable SD Card on Mac

Before attempting to repair a corrupted SD card on your Mac, it’s important to take a few preliminary steps to avoid further damage. These steps provide you with increased chances of successful recovery of your data.

1. Stop using the SD card immediately. Continuing to use a corrupted SD card can overwrite existing data, making recovery more difficult. Disconnect the SD card from your device and avoid writing any new files to it until recovery efforts are complete.
2. Try a different card reader or USB port. If the SD card isn’t being recognized, the problem could lie with your card reader or the USB port. Connect the SD card to another reader or port to rule out hardware-related issues.
3. Check for physical damage. Inspect the SD card for visible signs of damage, such as cracks, scratches, or bent connectors. If the card shows physical damage, professional data recovery services may be required to retrieve the files.
4. Reboot your Mac. Sometimes, system glitches or background processes can interfere with the recognition of an SD card. Restarting your Mac refreshes its resources and may help resolve the issue of an unreadable SD card.
5. Clean the SD card and its slot. Dust or debris inside the SD card slot can prevent proper contact between the card and your Mac. Use a soft, dry cloth to clean the card and carefully remove any dust from the slot.
6. Check for hidden files. It’s possible that your files aren’t missing or corrupted but simply hidden from view. To reveal hidden files on macOS, open Finder on your Mac. Press Command + Shift + Period (.) on your keyboard. Hidden files will now be visible. You can check if your missing files appear in this view. If the files show up, they may have been hidden due to an issue with the file system. Once you recover them, you can unhide them permanently by renaming the files and removing the leading period (.) in their filenames.
7. Check the SD card on another device. If possible, test the SD card in another Mac, PC, or camera to see if the issue persists. This helps confirm whether the card itself is faulty or if the problem is specific to your Mac.

How to Recover Data from a Corrupted SD Card on Mac

In our experience, before attempting any repair on a corrupted SD card, recovering your data should be the top priority. Repairing a corrupted SD card can often lead to data being overwritten or permanently lost, so it’s important to secure your files first. We always recommend, in the case of corrupted storage devices, to create a backup or image of the drive to prevent further data loss.

For such cases, a great tool that has highly recommended itself is Disk Drill. It’s one of the most popular SD recovery software solutions and stands out for its versatility and ease of use.

Disk Drill can recover data even from SD cards that don’t show up in Finder. In situations where the SD card appears to be completely unrecognizable by macOS, Disk Drill works behind the scenes to interact with the card on a lower level. Using its data scanning algorithms, Disk Drill locates the file structure and retrieves the hidden data, even when Finder cannot access it.

SD cards are commonly used to store files like photos, videos, documents, and audio recordings. Disk Drill excels at recovering these types of files, whether it’s a photo album from a family trip, important work documents, or videos captured on a camera, Disk Drill can recover over 400 different file types, including JPEG, RAW, MP4, MOV, and many more.

Disk Drill comes in several versions. The free version allows you to scan your SD card and preview the recoverable files, which helps you see what can be restored. However, to actually recover those files, you will need to upgrade to the Pro version. This upgrade provides access to full data recovery functionality, enabling you to save the files onto your Mac after scanning.

How to recover corrupted SD card data on Mac using Disk Drill:

1. Head to the official Disk Drill website and download the macOS version. Install it on your Mac, following the instructions provided.
2. Insert the corrupted SD card into a card reader and connect it to your Mac.
3. Open Disk Drill and allow the software to detect your SD card.
4. Select “Byte-to-byte Backup” from the sidebar, choose the SD card, and click “Create Backup.”
5. After creating the backup, return to the main Disk Drill window. Select “Attach disk image” at the bottom of the screen, then locate and select the SD card image you just created.
6. Click “Search for lost data” to begin the scanning process. Disk Drill will analyze the backup image to locate any recoverable files.
7. Once the scan is complete, click “Review found items” to see the list of recoverable files. Disk Drill allows you to preview each file to verify its integrity before recovery.
8. Use the checkboxes next to each file to select the ones you want to recover. If you wish to recover all files, select the top checkbox to mark everything.
9. Click the “Recover” button, then choose a destination folder on your Mac where Disk Drill will save the recovered files.

How to Fix a Corrupted SD Card on Mac

Once you’ve recovered the data from your corrupted SD card, it’s time to attempt fixing the card itself. macOS offers several effective methods to help restore a corrupted SD card and get it working again. Let’s walk through the different ways you can fix your SD card on a Mac.

Method 1: Use First Aid in Disk Utility to Repair SD Card on Mac

The First Aid feature in Disk Utility is one of the easiest and most reliable tools for fixing a corrupted SD card on macOS. It can repair basic errors in the SD card’s file system and is usually the first method to try.

1. Go to Finder, select Applications, then navigate to Utilities. Open Disk Utility from there.
2. In the left-hand sidebar, locate and select your SD card from the list of connected drives.
3. Click the First Aid button at the top of the window. Disk Utility will ask if you want to run the tool. Confirm your choice.
4. Disk Utility will scan the SD card for errors and attempt to repair them. Once the process is finished, it will notify you whether the repair was successful or not.
5. If First Aid reports that the repair was successful, eject the SD card and reinsert it to check if it functions normally.

This method is a quick fix for minor corruption issues and works best when the file system is still largely intact.

Method 2: Use Terminal to Recover Corrupted SD Card on a Mac

If First Aid is unable to repair the SD card, it’s time to move on to a more advanced method. The Terminal provides a deeper level of access to your SD card. It allows you to run command-line tools that can help repair more complex file system errors.

Even if you’ve never used Terminal before, we’ll show you detailed steps to help you repair your SD card. Simply follow along, and you’ll see that it’s not as complicated as it might appear:

1. Go to Finder, select Applications > Utilities, and then launch the Terminal app.
2. In Terminal, type “diskutil list” and press Enter. This will show a list of all the drives connected to your Mac, including your SD card.
3. Locate your SD card in the list and take note of its identifier (for example, it might be labeled as “/dev/disk2”). This identifier is important for the next steps.
4. To verify if the SD card has errors, type “diskutil verifyVolume /dev/disk2” (replacing “/dev/disk2” with your SD card’s actual identifier) and press Enter. This will check the card for any file system issues.
5. If the system finds errors, you can fix them by typing “diskutil repairVolume /dev/disk2” (again, using your SD card’s identifier) and pressing Enter. Terminal will then attempt to repair the card and report back on the status once complete.
6. After the repair process finishes, safely eject the SD card and reconnect it to your Mac to check if it’s functioning normally.

Method 3: Format the Corrupted SD Card on a Mac

If previous repair attempts didn’t work, formatting the SD card may be the final option. Formatting completely removes the file system and reinstalls a fresh one, clearing all corruption in the process. Keep in mind, that this process will erase all data on the card, so you must have already recovered everything you need. For formatting, you can use the already familiar Disk Utility.

1. Go to Finder, navigate to Applications, then Utilities, and open Disk Utility.
2. Select your SD card.
3. At the top of the Disk Utility window, click the Erase button. This action prepares the SD card for reformatting, allowing you to change its structure and fix any file system issues.
4. Choose format. For SD cards larger than 32GB, select ExFAT as the format. ExFAT is a modern file system that supports large capacities and is compatible with both macOS and Windows. For SD cards 32GB and smaller, select MS-DOS (FAT) (also known as FAT32). This format works well with smaller cards and is widely compatible with older devices.
5. Click Erase after selecting the appropriate format and scheme. Disk Utility will begin reformatting the SD card, completely wiping its file system and preparing it for future use.
6. Once the formatting process is complete, Disk Utility will notify you. Eject the SD card and reinsert it to verify that it’s functioning correctly.

Formatting completely replaces the file system on your SD card, fixing any deep-seated corruption or structural damage caused by improper ejections or other issues. However, if formatting didn’t resolve the problem and the SD card remains unusable, this indicates that there’s likely physical damage. Unfortunately, at this point, none of the DIY methods can save the card, and it might be time to consider purchasing a new one.

Tips to Prevent Future SD Card Corruption

Prevention is always more efficient than trying to recover data or repair a damaged SD card. The good news is that most cases of SD card corruption can be avoided with careful handling and a few best practices. Below, we’ll provide more detailed advice, building on what we’ve already discussed throughout this article:

• Eject the SD card safely. As discussed earlier, improper ejection is one of the main causes of corruption. Always eject your SD card through macOS’s “Eject” function before physically removing it. The sudden removal of the card during an active read/write operation can corrupt the file system, leading to unreadable files.
• Avoid removing the card during data transfers. Data transfers are critical moments for SD cards, and interrupting them can cause major issues. Removing the card during a file transfer can result in incomplete data writes, leading to file fragmentation or total corruption. Wait until your Mac confirms the data transfer is finished and safely remove the card afterward to avoid this problem.
• Store the card properly. SD cards are vulnerable to environmental factors. They are designed to operate within certain temperature ranges—typically between -25°C and 85°C (-13°F to 185°F). Extreme temperatures, moisture, and dust can cause physical damage or corruption. Storing your SD card in a protective case shields it from environmental hazards. For example, if you’re working in a hot desert or freezing arctic conditions, make sure to monitor the card’s exposure to these elements.

• Limit use to one device. Professional photographers often use SD cards exclusively with one device, such as a camera, to avoid file system conflicts. When you use the same SD card across multiple devices (like switching it between a camera and a computer), each device might apply different formatting or writing behaviors, which can lead to compatibility issues and file system corruption. Sticking to one device helps maintain file integrity and reduces the risk of errors.
• Back up your data regularly. Instead of relying solely on your SD card, we recommend transferring your data to an external drive for safe storage. SD cards have a limited number of write cycles, and wear can accumulate over time, making regular backups necessary. Using an external drive allows you to store large files without overusing your SD card’s memory, extending its lifespan. Regularly moving your files to a reliable external storage device will help preserve your data in case the SD card fails.

Conclusion

No matter the type or brand of your SD card, the detailed steps we’ve provided will guide you through fixing the issue, even if you’ve never dealt with this type of problem before. Remember to incorporate our tips into your regular SD card handling to prevent future issues and keep your data safe.