Why does my phone say "SD card error" or that the card is corrupted?

Last reviewed: October 22, 2026 · Markdown version

Sometimes the card really is failing, but often the phone simply cannot read what is on it: a file system it does not support, encryption made by another phone, or a card set up as one phone's internal storage. Those cards are not broken, and the phone's offer to format them would wipe files you can still rescue elsewhere. So the rule is copy first, format last.

Samsung's checklist, in its order

Samsung's troubleshooting page has a section for exactly this message, headed "SD card is corrupted or not recognized". Its steps: take the card out and put it back, making sure it sits properly in the tray; then "Test the card with another device", adding that "Sometimes, a PC will have higher compatibility with file systems not supported by Android"; and only then format it, after you "test it with another device and back up any important data" (Issues with SD cards on Samsung phone or tablet, Samsung US, read 22 October 2026). For a warning that keeps coming back, the same page is blunt: "A malfunctioning SD card can cause data loss and device performance issues. It should be replaced or removed."

Three reasons a healthy card can look corrupted

The file system. Samsung lists FAT32 and exFAT as the compatible ones and says "NTFS (common on Windows PCs) and APFS (common on Macs) are not compatible" (MicroSD cards and your Galaxy phone or tablet, Samsung US, read 22 October 2026). A card formatted on a computer in one of those can read perfectly well on that computer and be rejected by the phone.
Encryption from another phone. On a Galaxy you can encrypt the card, and Samsung explains the catch: an encrypted card "can only be read on the device that was used to encrypt it", and after a factory reset the phone "will no longer be able to read the microSD card". Its advice is to decrypt the card before a reset or before using it in another device (same Samsung page).
A card adopted as internal storage. Android's help lists, for a card formatted as internal storage, "You can't transfer the SD card between devices" (Get started with an SD card, Android Help, read 22 October 2026). Moved into a new phone, such a card cannot be read there.

None of the Google pages we read uses the word "corrupted" or explains that message; they are silent on it (the Get started page above and Troubleshoot: SD card undetected issue, Files by Google Help, read 22 October 2026). Samsung's is the page that names it.

What to do, in order

Do not tap Format yet. Whatever the message offers, formatting is the step that cannot be undone.
Reseat the card. On a model whose slot sits under the back cover, Samsung's microSD page starts with "Turn your phone off" (its XCover6 Pro steps).
Try it in a computer's card reader. If the files are visible there, copy them off before anything else.
If it came from another phone, put it back in that phone and decrypt it or format it as portable storage there.
Format only once the files are safe, and if the error returns on a freshly formatted card, replace the card, as Samsung advises.

If the phone then refuses to format the card at all, that has its own causes and page.