You plug a USB drive into your Android phone and nothing happens: no notification, no drive in your file manager. It's frustrating, but it's almost always one of a handful of causes, and most take a minute to rule out.
Work through the checks below in order. They're sorted by how often each one turns out to be the problem.
First: is it really not detected?
When a drive connects properly, Android usually shows a notification, and the drive appears in your file manager:
- Files by Google (Pixel and many other phones): under Browse, as a USB drive.
- Samsung My Files: as USB storage.
- Settings → Storage: listed alongside internal storage on many phones.
If the drive appears in any of these, the phone is detecting it — skip to "It shows up but won't save files" below.
1. Try another cable or adapter
This is the most common cause by far.
Many USB-C cables and cheap adapters only carry power, not data, and they look identical to ones that do. The phone charges the drive, the drive's light may even come on, and nothing appears.
- Use a known-good USB-C OTG adapter or a drive with a USB-C plug built in.
- If you're using a hub or dongle, try the drive without it.
- If you have another drive or a USB keyboard, try it with the same adapter. If that fails too, the adapter is the likely culprit.
2. Check whether your phone has an OTG setting
On most Android phones, OTG — the feature that lets a phone read USB devices — works automatically. But some brands add a switch, and leave it off:
- OPPO and Realme: look for OTG connection, usually under Settings → Additional settings.
- OnePlus: look for an OTG storage setting in Settings.
Menu names vary by model and software version, so searching Settings for "OTG" is often quickest.
On these phones the switch turns itself off after about ten minutes of inactivity. If a drive worked earlier and now doesn't, check whether the setting has switched off again.
3. Check power
A phone supplies limited power through its port. Flash drives and small SSDs are usually fine, but portable hard drives — the kind with spinning disks — and some larger SSDs can need more than the phone provides.
The signs are a drive that doesn't appear at all, or one that appears and then disconnects, sometimes partway through a copy.
The fix is to power the drive separately: use a powered USB hub, or a drive with its own power supply.
4. Check the drive's format
A drive can connect perfectly and still not be usable, because Android can't read its format.
- exFAT and FAT32 work on nearly all Android phones.
- NTFS, common on drives used with Windows, is often read-only on Android and sometimes not supported at all.
- APFS and HFS+ (Mac formats) and ext4 (Linux) generally aren't supported.
If Android says the drive is unsupported and offers to format it, stop and think first: formatting erases everything on the drive. If it holds files you need, copy them off on a computer, then reformat the drive as exFAT — on Windows through File Explorer, or on a Mac with Disk Utility. exFAT vs FAT32 for phone backups explains the formats and how to reformat.
5. Check the drive and the port
- Try the drive on a computer. If it doesn't work there either, the drive itself may have failed.
- Look inside the phone's USB-C port. Pocket lint packs into ports and stops plugs from seating fully. Clean it gently with a wooden toothpick or a soft brush — never anything metal.
- Try a different drive to see whether the problem follows the drive or the phone.
6. Restart, and confirm OTG support
Restart the phone and try again — it clears more USB problems than it should.
Nearly every Android phone made in the past decade supports OTG, and any phone with a USB-C port almost certainly does. If a known-good drive, adapter, and USB keyboard all fail, the phone may be one of the few models without it.
It shows up but won't save files
If the drive appears but copying to it fails:
- It's read-only, usually because it's formatted NTFS. Reformat as exFAT after copying anything important off it.
- Small files copy but big videos fail. The drive is FAT32, which can't hold any single file over 4 GB. Reformat as exFAT.
- It disconnects mid-copy. Almost always power, a loose connection, or — on OPPO, Realme, and OnePlus phones — the OTG setting switching off. Use a powered hub and check the setting.
Once it's detected: how VaultDrive helps
VaultDrive backs up your photos and videos straight from your Android phone to a USB drive. It can't find a drive your phone doesn't detect — it uses Android's own storage access, like every app — but once the drive shows up, it takes care of the problems that usually come next:
- Choose the drive once. VaultDrive keeps permission to the drive you pick, so later backups don't ask again.
- It checks the format for you. VaultDrive warns you if the drive is FAT32 (4 GB file limit), NTFS (usually read-only), read-only, or in a format that may not be supported — recommending exFAT, with an in-app guide to reformatting.
- A disconnect isn't a disaster. If the drive drops out mid-backup, VaultDrive treats it as an interruption, not a failure: it tells you the drive was disconnected, and Reconnect & Resume picks up where it stopped. Files are written whole or not at all, so there are no half-copied files left behind.
- It keeps going with the screen off. Backups run in the background with progress, pause, and cancel in a notification.
- It covers your whole library — camera, screenshots, other apps' folders, and with Pro, WhatsApp media — mirroring your phone's folder structure on the drive.
- Every copy is checked against the original's size, with an optional SHA-256 hash check, and one bad file doesn't stop the run.
It's free for up to 200 files or 2 GB per backup, and Pro is a one-time purchase. For the full walkthrough, see how to back up Android photos to a USB drive.
Frequently Asked Questions
Why is my Android phone not detecting my USB drive?
The most common causes are a cable or adapter that only carries charge, an OTG setting that is switched off on some brands, a drive that needs more power than the phone supplies, and a drive format the phone can't use. Try a known-good OTG adapter first, then check for an OTG setting, then try a powered hub, and finally check the drive's format on a computer.
How do I turn on OTG on my Android phone?
On most Android phones OTG works automatically with no setting to change. Some brands add a switch: on many OPPO and Realme phones it is called OTG connection, under Settings then Additional settings, and OnePlus phones have a similar OTG storage setting. On these phones the switch turns itself off after about ten minutes of inactivity, so it may need turning on again.
Why does my USB drive keep disconnecting from my Android phone?
Usually because the drive needs more power than the phone supplies, especially a portable hard drive, or because of a loose connection or worn adapter. On OPPO, Realme, and OnePlus phones, the OTG setting can also switch itself off after about ten minutes without use. A powered USB hub or a self-powered drive fixes the power problem.
My phone says the USB drive is unsupported. What should I do?
It usually means the drive's format isn't one the phone can use, such as NTFS or a Linux format. Don't let the phone format it if it holds files you need, because formatting erases everything. Copy the files off on a computer, reformat the drive as exFAT, and it will work with the phone.
Does every Android phone support USB OTG?
Nearly every Android phone from the past decade does, and any phone with a USB-C port almost certainly does. A small number of budget models leave it out. If a known-good drive, adapter, and USB keyboard or mouse all fail to work, the phone may not support it.
Can VaultDrive find a USB drive my phone doesn't detect?
No. VaultDrive uses Android's own storage access, so if the phone doesn't detect the drive, no app can see it. Once the phone detects it, VaultDrive remembers the drive, checks its format, warns about FAT32, NTFS, and read-only drives, and if the drive disconnects mid-backup, lets you reconnect and resume where you left off.
The short version
Work through it in order: a data-capable cable or OTG adapter, the OTG setting on OPPO, Realme, and OnePlus phones (it switches itself off after ten minutes), power for hard drives, then the drive's format — exFAT works; NTFS usually doesn't.
Once the drive shows up, VaultDrive remembers it, warns you about the wrong format before you start, and if the drive drops out mid-backup, lets you reconnect and resume instead of starting over.