What to do if Galaxy S9 Plus won’t detect or recognize an SD card

This post addresses another common problem for smartphones of sometimes not being able to read or detect SD cards. While the post specifically mentions the Galaxy S9 Plus, the suggestions below can also be applied to other Samsung Galaxy devices.

Problem: Galaxy S9 Plus won’t detect or recognize an SD card

Hello, I’m hoping that you could help me out here. I have a Galaxy S9+ and have had this phone for just over a year now. I have had the same micro SD card in it from day one also. My issue is that for whatever reason today my phone stopped registering the sd card. Last night I had removed it to back up files onto my computer and then I inserted it back in the phone like I always do. As far as I know, it was fine. But in all honesty, I didn’t look it over either. But anyway, I noticed it was not mounted today. I took it out, checked it, reinserted it, and same problem – doesn’t register. Not listed in storage. It’s as if there is no card. I tried mounting it back on my computer and it did just fine. So i tried a spare sd card I had and put that in the phone. Same thing – like there is nothing there. It’s on the same tray with my verizon SIM and the SIM works just fine. So I just don’t understand what’s wrong here. Please help?

Solution: If your computer recognizes the SD card fine and reads all files in that card without any hint of corruption, then the issue must be with your Galaxy S9 Plus. Below are the things that you can do to troubleshoot the issue.

Force reboot

A quick force restart may help. In this case though, we suggest that you refresh the system by simulating a “battery pull” instead of a regular restart. Here’s how it’s done:

Press and hold the Power + Volume Down buttons for approximately 10 seconds or until the device power cycles. Allow several seconds for the Maintenance Boot Mode screen to appear.
From the Maintenance Boot Mode screen, select Normal Boot. You can use the volume buttons to cycle through the available options and the lower left button (below the volume buttons) to select. Wait for up to 90 seconds for the reset to complete.

Wipe the cache partition

Android uses a system cache, which is stored in the cache partition, to load apps quickly. Sometimes, this cache gets corrupted during and after an update, or for some other reasons. While this may sound harmless, a corrupted cache can eventually cause performance issues as well as a bunch of other minor annoyances. To ensure that your phone’s system cache is fresh, you can wipe the cache partition. This will force the phone to delete the current cache and replace it with a new one over time.

To wipe the cache partition on your Note8:

Turn off the device.
Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
When the green Android logo displays, release all keys (‘Installing system update’ will show for about 30 – 60 seconds before showing the Android system recovery menu options).
Press the Volume down key several times to highlight ‘wipe cache partition’.
Press Power button to select.
Press the Volume down key until ‘yes’ is highlighted and press the Power button.
When the wipe cache partition is complete, “Reboot system now” is highlighted.
Press the Power key to restart the device.

Clear cache and data of Device Maintenance app

Your Galaxy S9 Plus uses Device Maintenance app to access contents of your SD card. Just like any other app, this one may become bugged. To see if it has a cache issue, try to clear the app’s cache first. Here’s how:

Open Settings app.
Tap Apps.
Tap on More settings at the upper right (three-dot icon).
Select Show system apps.
Find and tap your app.
Tap Storage.
Tap Clear cache button.
Restart your S9 and check for the problem.

If the problem continues after wiping the cache, your next is to restore the app’s settings to its defaults. You can do that by clearing its data. Follow these steps to do that:

Open Settings app.
Tap Apps.
Tap on More settings at the upper right (three-dot icon).
Select Show system apps.
Find and tap your app.
Tap Storage.
Tap Manage Storage.
Tap Clear data button.
Restart your S9 and check for the problem.

Check in Safe Mode

One other reason why your S9 Plus may not be detecting the presence of an SD card is apps. To check if one of your downloaded apps is interfering with Android, restart your S9 Plus to safe mode. Here’s what you need to do exactly:

Turn the device off.
Remove the SD card from the phone. If it’s already removed, then don’t insert it yet.
Press and hold the Power key past the model name screen.
When “SAMSUNG” appears on the screen, release the Power key.
Immediately after releasing the Power key, press and hold the Volume down key.
Continue to hold the Volume down key until the device finishes restarting.
Safe mode will display in the bottom left corner of the screen.
Release the Volume down key when you see Safe Mode.
Insert the SD card.
Mount the SD card properly under Settings and check for the problem.

If your S9 Plus detects the SD card in this mode, then that means you have a bad app issue. To identify which of your apps is causing the trouble, you should boot the phone back to safe mode and follow these steps:

Boot to safe mode.
Check for the problem.
Once you’ve confirmed that a third party app is to blame, you can start uninstalling apps individually. We suggest that you begin with the most recent ones you added.
After you uninstall an app, restart the phone to normal mode and check for the problem.
If your S9 is still problematic, repeat steps 1-4.

Reset All Settings

This procedure mimics the effect of a factory reset without actually deleting personal data. If the problem is due to a simple, minor bug in the system, this might help. To do this, follow the steps below:

From the Home screen, swipe up on an empty spot to open the Apps tray.
Tap General Management > Reset settings.
Tap Reset settings.
If you have set up a PIN, enter it.
Tap Reset settings. Once complete a confirmation window will appear.

Factory reset

This is a drastic solution but this should be the most effective solution for this type of problem. As there’s no hardware malfunction or kernel-level issue, you can bet factory reset will help.

Create a backup of your data.
Turn off the device.
Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
When the green Android logo displays, release all keys (‘Installing system update’ will show for about 30 – 60 seconds before showing the Android system recovery menu options).
Press the Volume down key several times to highlight ‘wipe data / factory reset’.
Press Power button to select.
Press the Volume down key until ‘Yes — delete all user data’ is highlighted.
Press Power button to select and start the master reset.
When the master reset is complete, ‘Reboot system now’ is highlighted.
Press the Power key to restart the device.
Check for the problem.

Get Samsung support

If the problem returns right after a factory reset, bad hardware or firmware coding issue must be behind it. Let Samsung handle it from here on.