| Previous | Next |
| ERROR_INVALID_USER_BUFFER | ERROR_NO_TRUST_LSA_SECRET |
ERROR_UNRECOGNIZED_MEDIA
The storage media is present but its format is not recognized.
ERROR_UNRECOGNIZED_MEDIA is Win32 error 1785 (0x6F9). The device may be reachable while the media’s partitioning, file system, geometry, or on-disk metadata cannot be interpreted by the component performing the operation. This is different from “no media in drive.” It can represent expected blank or foreign media, physical read damage, unsupported format, encryption, or corruption.
Typical causes
- the disk is blank, uninitialized, or formatted for an unsupported operating system
- partition or file-system metadata is damaged or partially overwritten
- the wrong sector size, removable-media profile, or legacy format is reported
- encryption or vendor-specific formatting hides recognizable file-system structures
- the reader, cable, adapter, firmware, or media has intermittent read failures
Storage evidence to retain
Capture device instance and model, bus and adapter, media type, capacity, logical and physical sector sizes, partition style, volume identifiers, first failing offset, system and storage event logs, firmware and driver versions, and whether another known-good medium works in the same reader. Do not initialize, format, or run repair tools before imaging important media.
Diagnostic sequence
Confirm media presence and read-only status, then compare behavior with another reader and another medium. Inspect disk and partition metadata without writing to the device. Determine whether Windows sees the expected capacity and sector geometry. A zero or implausible size points toward transport or controller problems rather than only a file-system issue.
If data matters, acquire a sector image using an appropriate forensic or recovery workflow and work from the copy. Check whether the medium uses a supported file system or requires vendor software. Correlate bad-block and reset events with the exact time of error 1785.
Recovery choices
For expendable blank media, initialize and format it only after confirming the correct target device. For valuable media, stop repeated writes and use backup or recovery procedures. Update the reader driver or firmware when failures follow hardware rather than one medium.
Applications should distinguish unrecognized, absent, write-protected, and corrupt media and should never offer automatic formatting as the default response. Record enough device identity to prevent an operator from acting on the wrong disk.
Difference from an unrecognized volume
ERROR_UNRECOGNIZED_VOLUME is usually associated with a mounted volume whose file system Windows cannot recognize. Error 1785 can be raised at a broader media or device operation level before a usable volume exists. ERROR_NO_MEDIA_IN_DRIVE means the medium is absent.
Example
A USB card reader appears normally, but one memory card returns 1785 and reports inconsistent capacity across reconnects. Another card works in the reader. The operator images the failing card through a recovery device rather than formatting it, revealing controller-level media failure.
References
Looking for a different code? Search another status or error code.