Error code
macOS -69888
MACOS-69888
System Error Code· A POSIX/system errno returned when a system call fails.
What it means
Could not unmount disk — Disk Utility cannot unmount the volume needed for repair..
How to fix it
- Boot into macOS Recovery and run First Aid from there.
- force-unmount with `diskutil unmountDisk force /dev/diskX`.
- quit all apps that may be accessing the volume.
- disable Time Machine temporarily.
Not affiliated with macOS. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
More macOS codes
- -69716APFS snapshot error — an APFS snapshot could not be created or rolled back.
- -69845Disk Utility First Aid failure — the APFS file system could not be verified or repaired.
- -10004Application not found (Launch Services) — no registered handler exists for the bundle identifier or URL scheme.
- -108Not enough memory (memFullErr) — the system could not allocate the requested heap space.
- -10810Cannot open application — the Launch Services framework failed to open the requested app.
- -120Directory not found (dirNFErr) — the specified directory path does not exist.
- -128User cancelled operation (userCanceledErr) — the user dismissed a dialog or pressed Command+Period to stop the operation.
- -1708Apple Event not handled (errAEEventNotHandled) — the target app has no handler registered for the received Apple Event.
- -1712Apple Event timeout (errAETimeout) — an inter-process Apple Event did not receive a reply within the allowed time.
- -192Resource not found (resNotFound) — the Resource Manager could not locate a requested resource handle.
- -25291Screen is locked — a Keychain or security operation requires an unlocked screen.
- -25307Security framework error — a Keychain or certificate trust operation returned an unexpected error.