To fix an SD card reader that is not working, check the card’s fit and compatibility, reconnect the reader, then check whether your device detects the card before updating drivers or repairing it. Test the card in another compatible device to help separate a card problem from a reader problem. The Windows steps below use Windows 11 menus.
Back up accessible files before repairs that write to the card, and save formatting for last because it erases the contents. Do not initialize or repartition a previously populated card just because Windows cannot read it.
The short version
- Start with the connection: Check the card, adapter, reader connection, and model compatibility.
- Check detection: Use Disk Management on Windows or Disk Utility on Mac to see whether the card is recognized.
- Follow the symptom: A missing drive letter, blocked accessory, or app permission needs a different fix from a driver error.
- Protect your files: Back up accessible data before repair and format only after saving needed files.
| Fix | When to use it |
|---|---|
| Check compatibility and clean contacts | Dell integrated reader cannot read the card |
| Reseat the card and check its adapter | Card fails to mount in a Mac SDXC slot |
| Reconnect the USB reader and check power | Mac USB reader fails or shows a power error |
| Restart Windows and try another PC | You need to distinguish a card problem from a Samsung reader problem |
| Bring the card online | Windows Disk Management shows Offline |
| Assign a drive letter | Accessible Windows volume has a missing or conflicting letter |
| Enable the reader in Device Manager | Device status reports Code 22 |
| Install optional Windows drivers | A reader update appears in Optional updates |
| Update through SupportAssist | Supported Dell PC needs applicable updates |
| Download a Dell driver package | You need the package for your model and operating system |
| Run Dell’s website scan | Supported Dell PC has the required SupportAssist components |
| Install an extracted manufacturer driver | You have a compatible Windows reader driver |
| Reinstall the reader device | Samsung PC still fails after driver checks |
| Enable the reader in BIOS or UEFI | Dell model exposes a reader-enable setting |
| Approve the accessory | Apple-silicon Mac laptop requests permission |
| Reveal the Finder sidebar | Mounted card is hidden from view |
| Mount the volume in Disk Utility | Mac detects the card but has not mounted it |
| Disconnect other Mac peripherals | Disk Utility cannot detect the card |
| Update macOS | A compatible update is offered |
| Unlock and reconnect on iPhone or iPad | Storage accessory cannot be accessed |
| Open the card in iPhone Files | You need to separate storage access from a Photos import problem |
| Reset the camera-adapter connection | Apple camera adapter has trouble on iOS 18 |
| Allow access in Files by Google | Compatible Android USB reader needs permission |
| Update ChromeOS | Eligible Chromebook has an available update |
| Check ChromeOS compatibility or transfer through Drive | Another computer can read the card |
| Mount through GNOME Files | Card needs mounting on a GNOME desktop |
| Restore Windows app permissions | A permission-controlled app cannot access files |
| Restore Mac app permissions | An app needs access to the listed storage location |
| Allow Chromebook Android app access | Files opens the card but an Android app cannot |
| Run Windows error checking | Detected card has filesystem errors |
| Run Mac First Aid | Detected card has filesystem or directory damage |
| Format in Windows | Detected card still needs formatting after files are saved |
| Erase in Mac Disk Utility | Card needs a compatible format and partition scheme |
| Format in Chromebook Files | Detected card has an unrecognized or unmountable partition |
| Format in the original camera | Camera card has data or formatting problems |
Check the card and reader connection
For a Dell integrated reader, check your computer’s model-specific manual for supported card types and capacities, then inspect the card and slot for damage. Dell recommends electronics-safe compressed air for the slot and a lint-free cloth with suitable contact cleaner for dirty card contacts. Follow your own manufacturer’s cleaning instructions for other readers.
On a Mac with a built-in SDXC slot, remove and reinsert a card that fails to mount without forcing it. Insert it with the contacts facing downward toward the computer, and use the appropriate adapter for microSD or miniSD cards. Test the card in another compatible device before moving to software repairs.
For a USB reader connected to a Mac, disconnect and reconnect the reader, then try another USB port. Connect it directly instead of through a USB or Thunderbolt hub, particularly if you see a power error or USB Devices Disabled. If you use a self-powered hub, connect its AC adapter.
Restart a Windows 11 PC by right-clicking Start and selecting Shut down or sign out > Restart. Samsung also recommends testing the card in another PC. For a Samsung PC, replace a card that fails in other PCs; if the original PC still fails after troubleshooting, request service.
Find a missing card in Windows
Right-click Start and open Disk Management, then identify the card by its capacity and inspect its status. When its disk entry shows Offline and offers Online, right-click that entry and select Online. If the card is absent, continue with reader and driver checks.
For an accessible, initialized card volume with a missing or conflicting drive letter, use administrator permissions to assign an unused letter. Right-click the volume and select Change Drive Letter and Paths, then choose Add or Change. Select Assign the following drive letter, choose an unused letter, select OK, then select Yes.
If the card is detected but its files remain inaccessible, protect any files you can access before moving to filesystem repair. Avoid treating an unreadable card containing files as a new, empty disk.
Enable or update the Windows reader
Press Windows + X and select Device Manager, then inspect the reader. On Samsung PCs, it is commonly under SD host adapters, but the category and device name vary by model. If its status reports Code 22, select Enable Device; this applies specifically to a device disabled through Device Manager.
To check for optional reader drivers, open Start > Settings > Windows Update > Advanced options > Optional updates. Select the applicable reader-driver entry, choose Download and install, and restart afterward. Optional driver updates are not installed automatically, and the entry’s wording depends on your hardware.
For a supported Dell Windows PC, open SupportAssist and select Home > Update software > Start, then install applicable updates. Alternatively, open Dell Drivers & Downloads, identify your PC by Service Tag or model, and follow the reader package’s installation instructions. Select a package offered for your model and operating system.
For Dell’s website scan, under Automatic Updates, select Check for updates and complete the SupportAssist scan and applicable installations. This requires administrator access and compatible SupportAssist components. Use SupportAssist or the website scan in place of the retired Dell Update and Alienware Update workflows.
A manually downloaded Windows 11 driver must match your PC model, Windows version, and architecture. Extract the manufacturer’s driver, right-click the reader in Device Manager, and select Update driver, then select Browse my computer for drivers and choose Browse.... Choose the extracted folder, select OK, then Next, and select Close when finished.
If a Samsung PC still fails, reinstalling removes the reader’s current device installation before Windows rediscovers it. Right-click the reader in Device Manager and select Uninstall device, then select Action > Scan for hardware changes or restart the PC. Locate the reader by its model-specific name if the expected category is missing.
On Dell models with a reader-enable setting in BIOS or UEFI, restart and repeatedly press F2 at the Dell logo. Find Secure Digital (SD) card, Card Reader, or SD Reader, enable it, then save and exit using your model’s documented controls. If you cannot find that setting, check the model’s manual before continuing with other reader checks.
Approve and mount the card on a Mac
On an Apple-silicon Mac laptop, unlock the Mac, reconnect the reader or SD card, and select Allow. Reconnecting presents the approval again if you previously rejected it. If accessory approval is controlled on a supervised Mac, ask your administrator.
A mounted card can be hidden in Finder. Activate the Finder window, select View > Show Sidebar, then hover over Locations and click its disclosure arrow to reveal connected devices. If the card remains missing from Finder, open Disk Utility; if its volume appears there but is unmounted, select it and click Mount.
When Disk Utility cannot see the card, shut down the Mac, disconnect nonessential peripherals, and retry. Check an external reader’s connections and power as well. Persistent non-detection may require hardware service.
For a compatible macOS update, open the Apple menu > System Settings > General > Software Update. Install the update offered for your Mac. If the card is detected but reports filesystem errors, proceed to First Aid below.
Restore access on a phone or tablet
On an iPhone or iPad, disconnect the compatible reader, unlock the device, then reconnect it. Apple says storage accessories always require unlocking before use. Changing accessory-approval preferences does not remove that storage requirement; ask IT about restrictions on a managed device.
On an iPhone, open Files, tap Browse, and select the card under Locations. If Locations is absent, tap Browse again. Being able to open the card here helps distinguish a working reader from a Photos import problem.
For an Apple camera adapter on iOS 18, disconnect the adapter for 30 seconds and reconnect it. Separately remove the card for 30 seconds and reconnect it, then restart the device and test another card. When only particular media fails, check format compatibility and whether the files were captured by a camera.
On Android 7.0 or later with compatible USB storage hardware, connect the reader and open Files by Google. Select the device when USB available appears, tap Allow, then tap the USB device under Storage devices. If the notification does not appear, disconnect and reconnect the reader.
Check Chromebook and GNOME access
On a Chromebook still eligible for updates, connect to Wi-Fi, select the time, and open Settings > About ChromeOS > Check for updates. Allow the update to download, then select Restart when offered. On a managed Chromebook, ask your administrator about controlled updates or external-storage restrictions.
Check the card’s filesystem against Google’s supported filesystem list for ChromeOS. If another computer reads the card, you can upload needed files to Google Drive and open them on the Chromebook. This retrieves your files but does not repair the reader.
On a Linux desktop using GNOME, open Files from Activities and select the card in the sidebar to mount it. Test another card or reader if needed. For an unsupported internal reader, GNOME recommends a USB external reader or connecting the camera or device directly by USB.
Fix access that fails in only one app
When an app governed by Windows filesystem permissions cannot access files, open Start > Settings > Privacy & security > File system. Turn on Let apps access your file system, then enable the affected app’s individual switch if listed. Many traditional desktop applications are exempt from this permission. If your organization controls the setting, ask IT to review it.
For a Mac app requesting location-specific access, open the Apple menu > System Settings > Privacy & Security > Files & Folders. Enable access to the applicable listed storage location for that app. The available switches depend on which access the app has requested.
If Chromebook Files can open the card but an Android app cannot, select the time and open Settings > System preferences. Under Storage and power, open Storage management > External storage preference. Turn on the card’s storage-device switch.
Repair errors on a detected card
Repairs can write changes to the card, so back up accessible files before proceeding. On Windows 11, open File Explorer and select This PC, right-click the detected card, and choose Properties > Tools. Under Error checking, select Check, then select Scan drive if offered; prompts depend on the filesystem and its condition.
On a Mac, back up accessible files, then open Applications > Utilities > Disk Utility and choose View > Show All Devices. Select the lowest volume belonging to the card, click First Aid, then click Run. Repeat upward for its other volumes, any containers, and finally the card itself.
These repairs apply to detected storage with filesystem or directory problems. When the card is absent from the device list, return to connection, compatibility, and hardware checks. If repair fails, preserve needed files before considering formatting.
Format only after saving your files
Formatting erases the card’s files, so back up or recover everything you need before continuing. On Windows 11, open This PC, right-click the detected card, and select Format. Choose a File system supported by the camera, phone, or other device that will use it, then select Start.
On a Mac, formatting destroys existing files, so back them up first. Open Disk Utility, choose View > Show All Devices, select the card, and click Erase. Choose the required Scheme and Format for the intended device, enter a name, click Erase, then click Done.
For a Chromebook card with an unrecognized or unmountable partition, formatting erases its files, so back them up elsewhere first. Open Launcher > Files, right-click the card in the left pane, and select Format device.
Formatting a camera card erases its contents, so first import or recover needed files using another device. Then use the original camera’s documented card-format command. Follow that camera’s manual for the exact menu labels and confirmations.
Frequently Asked Questions
Why can the card be read but its files cannot be changed?
A full-size SD card or adapter may have its physical write-protection slider locked. Eject and remove the card, move the slider to the unlocked position, then reinsert it. This addresses an inability to modify files, not an undetected reader.
Can a driver update cause the reader to stop working?
If the failure began after a driver update, Windows 11 can roll back to an available previous driver with administrator access. Rollback replaces the current driver with the previous version. Right-click Start, open Device Manager, right-click the reader, and select Properties > Driver > Roll Back Driver, then choose the reason, select Yes, and restart if prompted. If you cannot select a previous driver, use a compatible manufacturer driver instead.
What card formats can an iPhone read?
A compatible external card must have one data partition. Supported filesystems include APFS, encrypted APFS, HFS+, exFAT, FAT32, and FAT.
Which format does Apple recommend for sharing a card with Windows?
Apple specifies MS-DOS (FAT) for disks up to 32 GB and ExFAT for larger disks when sharing with Windows. The intended camera or other host must also support the chosen format and partition scheme.
