A complete SD card repair guide to fix corrupted SD card on Windows or Mac

Updated by Tim to Data Recovery Tips on June 22th, 2021

Summary: A complete SD card repair guide to fix corrupted SD card that can't be read on Windows computer and Mac. If your SD card is not reading or working, here you will learn how to fix the corrupted SD card on Windows or Mac.

SD cards are widely used in digital cameras, computers, and mobile phones. For instance, many Android phones use micro SD cards to expand storage capacity. However, the SD card won't be reading on phone or on Windows computer once it's corrupted. What's worse, such SD card corruption could freeze your computer. 

But you don't even know why this SD card became corrupted suddenly. To avoid incorrect solutions cause further data loss, this article lists 6 proven solutions to repair corrupted or unreadable SD card. At the same time, you can perform SD card data recovery so that you won't lose files when confronted with such SD card problems and errors.

Let's dive into details.

How to fix corrupted SD card on Windows 10/8/7?

When an SD card becomes corrupted, all contents stored on the SD card can't be read. For example, you may find that your SD card is not showing pictures on the camera or computer. If you try to open the corrupted SD card on Windows 10 computer, you will get some error messages such as 'File or directory is corrupted and unreadable' or 'The disk is not formatted. Do you want to format it now?' On a Mac computer, you may receive the error message "The disk you inserted was not readable by this computer".

Here is a user who experienced the same thing:

Hi All, we took tons of pictures on our personal point and shoot camera at my wedding. While taking the pictures, the immediate preview was available and there were never any error messages on the camera. However, none of our wedding pictures are available on the SD card anymore now. Are my photos gone forever? I've already tried Zero Assumption and it doesn't return any more pictures than what I can already see. Is there any other way I can fix this corrupted SD card and recover my pictures from this SD card? -- From Tom's Hardware Forums

In this situation, the first thing is to stop using the corrupted SD card immediately. And you should not format it directly, as reformatting will wipe your data off the SD card. Instead, fix the SD card with the folllowing ready-to-use solutions.

Note: If your micro SD card is not working or not reading on Android phones or on a camera, you can take it out and connect it to a computer via an SD card adapter. No special micro SD card repair tool for phones is needed.

Solution 1: Try a different SD card reader or computer

Sometimes, the SD card is not reading by Windows 10 or 8 computer because the SD card reader is not working. It's reasonable that your computer won't recognize the SD card when the SD card reader is not working. A functioned SD card reader can be viewed in Device Management.

Check SD card reader in Device Management

To check this, you can insert another SD card and see if the slot is working. If it's not working as well, try another SD card reader or even another computer. If your SD card is read by another SD card reader, you need to replace the problematic SD card reader.

Solution 2: Check the corrupted SD card in Disk Management

When SD card is not reading on a Windows computer due to corruption, you can check and fix it in Disk Management. Disk Management is a system utility that you can view all disk information like the file system, partition, drive letter, and storage capacity.

You may see three possibilities in Disk Management.

SD card doesn't have a drive letter

As you probably know, Windows needs to assign a drive letter before you can access SD card. But if your computer fails to assign a drive letter to the SD card, your SD card won't be read. To solve this problem, you need to assign a drive letter.

1. Right click My Computer or This PC -> Manage -> Storage -> Disk Management.

  • 2. Find the SD card and check if you can see the drive letter.
  • Check drive letter of the SD card in Disk Management

    3. Right click and check if the "Change Drive Letter and Paths..." option is available from the context menu.

    4. Click Add and follow the wizard to assign a drive letter to this SD card.

    Add drive letter to the SD card in Disk Management

    If you can assign a drive letter, the SD card will be read by your PC again. But if you can't assign a drive letter due to no option for this operation, you'd better recover data from the corrupted SD card to prevent data loss.

    SD card showing RAW file system

    Probably, your SD card is formatted with FAT32 or exFAT file system, but now it is showing as RAW file system in Disk Management.

    A RAW file system means that the file system is corrupted so that Windows operating system can't recognize it. Usually, you'll get error message like "You need to format this disk before you can use it". In that case, you can fix the RAW SD card by data recovery and reformatting.

    SD card not showing full size

    The worst thing is that SD card is not showing full size or SD card is not showing up in Disk Management. In this situation, SD card has physically failed, the computer won't recognize it. You need to send it to a local data recovery specialist if you have important files.

    Solution 3: Repair corrupted SD card with CHKDSK command

    CHKDSK is a built-in Windows utility that can check the integrity of your disk and can fix various file system errors. You can try to fix corrupted SD card using command. If you successfully repair the corrupted SD card by CHKDSK command, you will regain access to the SD card as well as to all your files.

    1. Plug your corrupted SD card into your computer with a card reader.

    2. Go to the Start menu of your Windows computer, type in "cmd" in the search bar, and press Enter.

    3. Right-click "cmd.exe" and choose "Run as administrator".

    4. Type in "chkdsk volume: /f" in the command prompt, where "volume" is the drive letter of your SD card. (For example, if the drive letter of your SD card is "G", then you need to type in "chkdsk G: /f".)

    After several minutes, you will see "Windows has made corrections to the file system" in the command prompt window. It means you have successfully fixed corrupted SD card, you can read SD card on your computer.

    How to fix corrrupted SD card with First Aid on your Mac?

    Solution 4: Fix corrupted SD card by reformatting

    When SD card can't be read, CHKDSK command coud fail to fix the corrupted SD card and reports the error message "CHKDSK is not available for RAW drives". In these cases, the file system of your SD card is severely damaged and CHKDSK command can't help. Thus, the only solution is to reformat the corrupted SD card.

    Tips: Reformatting will erase all data on the SD card. So, to prevent data loss, SD card data recovery is the first thing.

    How to format an SD card on your Windows computer?

    How to fix if you can't format an SD card?

    Solution 5: Check SD card warranty period

    When your SD card is not reading or corrupted, it is worth checking the warranty of your memory/SD card to see if it is still valid or not. If so, providing you don't have any important data stored on the SD card, it may be easier to simply seek a refund or replace the card with a brand-new one.

    Solution 6: Contact the manufacturer's support team for help

    If your corrupted SD card is not showing up on Mac or Windows Disk Management, it should be a hardware issue, please contact the manufacturer's support team for help, whether you want a product replacement or repair service.

    How to repair an unreadable SD card on Mac?

    Not many people like to format their external drives unless they have to, so as you. If you are looking for solutions for repairing the unreadable SD card without formatting, you will learn 5 methods in this section. We will walk you through the solutions one by one.

    Fix 1: Try a different SD card reader or slot

    A damaged SD card reader or slot can make the SD card not recognizable nor readable. At times, simply changing a card reader or slot can solve the problem.

    Try a different SD card reader or slot

    If the solution doesn't work, move forward to the next one.

    What to do if SD card reader is not working?

    Fix 2: Connect the SD card to another device

    Now you need to check if it is the problem of the memory card or your Mac computer.

    1. Disconnect the SD card from Mac.

    2. Connect the SD card to another device, i.e. a Mac or a camera.

    If it is readable on another device, then your Mac may have some encryption or driver-related issue with the SD card. On the other hand, if your SD memory card still doesn't work right on another device, then it is corrupted very possibly.

    Check the next method to see how to make the SD card readable on your Mac by updating the disk driver.

    Fix 3: Update disk driver

    A disk driver is a group of files that enable the disk to communicate with the operating system. Therefore, if the driver is too old on a Mac, the macOS can't send nor receive data correctly to the up-to-date memory card.

    Here is how to update the disk driver on Mac:

    1. Click on the Apple icon at the top menu bar and select "System Preferences…".

    2. Choose "Software Updates".

    3. Click on "Update Now" or "Update All" if you have multiple updates.

    After having updated the disk driver, your SD card should be readable now. If this doesn't solve the SD card not readable by Mac, MacBook Air, iMac, iMac Pro, Mac Pro or Mac mini problem, it might be because the SD card is encrypted. Check the next solution.

    Fix 4: Check if the SD card is encrypted

    This solution will tell you how to check whether the SD card is encrypted and solve the unreadable SD card problem on Mac. If your memory card is protected by third-party encryption software or non-Mac native encryption programs, then it can't be recognized on Mac. For example, if your memory card is encrypted by BitLocker, an encryption program developed by Microsoft and not supported by macOS, it will appear unreadable on Mac. Therefore, you will need to decrypt the SD card first using the according decryption software. Then reconnect the SD card to the Mac and your SD card should be readable on Mac.

    BitLocker Data Recovery: Recover deleted/lost files from BitLocker encrypted drives

    Fix 5: Run First Aid to repair the unreadable SD card

    If the methods above fail to fix the SD memory card that is not readable on Mac, the SD card may have some file system errors. Luckily, macOS has a built-in utility called First Aid to check disk error and repair the corrupted file system.

    Here is how to repair a non-readable SD card using First Aid in Disk Utility:

    1. Go to Finder > Applications > Utilities > Disk Utility.

    2. After launching Disk Utility, choose "View" from the upper right menu bar. From the drop-down menu, select "Show All Devices".

    Repair unreadable SD cards with First Aid

    3. Choose the unreadable SD card at the left sidebar and click on "First Aid".

    4. Click "Run". This will start the verification and repair process.

    Repair unreadable SD card with First Aid

    If Disk Utility reports that the disk appears to be OK or has been repaired, you're done. You can click "Done" to exit and then you can use your SD card as usual.

    However, First Aid can only fix minor file system issues. If the First Aid fails to repair the disk, the SD card has been corrupted seriously. Fixing the unreadable SD card by formatting could be your last option.

    Fix 6: Format the unreadable SD card

    Before you format your SD card, you should note that formatting a disk will write in new file system on the disk and make your disk appear blank.

    How to format an SD card on Mac?

    If you don't have any important files on it, go ahead to format it. But if you do have important data that you don't want to lose, remember to recover lost data from unreadable SD card.

    How to recover data from an unreadable SD card on Mac?

    After the formatting process completes, you just reconnect the SD card to the Mac and it should be readable by now.

    If the SD card can't be formatted, it means the card has been physically damaged. Unfortunately, there is no software can help you fix any hardware problem of an SD card. You can only send it to a local repair shop or replace it with a new one.

    Understanding how an SD card becomes corrupted

    Generally speaking, SD card not reading usually results from improper operation by human. So, you can recall if you have done those improper things to your SD card.

    • Turning off the camera before the photos are completely written to your SD, SDHC, SDXC, or Compact Flash card. If you have done this, your photos on the SD card may be corrupted, or what's even worse, the whole folder would be empty.
    • Camera's SD card corrupted
    • Removing the SD card when data transferring or photo edition is undergoing on computers. It's the same theory as the above one. The data would be in a buffer or cache sectors of your SD card, and you can't access it normally.
    • SD card data transfer interruption
    • Frequently insert and pull out the same SD card on different cameras. Such operation causes damage to both the chip of the SD card and the Camera's card reader.
    • Unsafely remove the hardware and eject the storage device. SD cards frequently get corrupted after abrupt removal. And you might get an error message on a Windows computer like 'drive is not accessible', 'you need to format the drive before you can use it', etc.
    • SD card corruption caused by unsafe ejection
    • Continually shooting and deleting images when the SD card is already full.
    • Sudden interruptions while formatting SD cards, etc. In this case, if you check the SD card in Disk Management, you'll find its file system is RAW.

    Those operations will corrupt your SD card and stop it working normally. Consequently, you can't write or even read your files on it.

    How to avoid SD card corruption in the future?

    As SD cards are so frequently used in our daily life, it's worthy mentioning the tips to prevent SD card corruption again in the future. Here are some tips for SD card maintenance.

    First, you should always eject an SD card on the computer by Safe Removal.

    Second, use different SD cards on different devices.

    Third, handle it gently.

    If unfortunately your SD card got corrupted and there were important files on it, such as wedding photos, toddlers videos, work files, etc., you can follow the tutorial on this page to recover deleted/lost photos from SD cards with M3 Data Recovery.

    Finally, the most economical and fool-proof method to avoid data loss is to back up your files regularly.