Windows System Log · Event 157
Event 157: A disk disappeared without being ejected
A drive stopped being present and Windows had no warning. On a USB stick that was yanked out, this is exactly what it says. On an internal drive that nobody touched, it means the disk dropped off the bus while the machine was running, which is a hardware problem.
Also written as Event ID 157 diskDisk has been surprise removedsurprise removal disk windowsdisk 157 error
- How oftenUncommon
- Vendor calls itWarning
- LogSystem
- Sourcedisk
What it means for you
On a personal computer
If you unplugged a USB drive or memory card, that is all this is. If it names a drive that lives inside your PC and you did not touch anything, the drive or its cable disconnected on its own — which is worth sorting out, because anything being written at that moment was lost.
For an analyst
On servers this is a backplane, HBA or cable fault far more often than a dead disk, and it frequently appears in pairs with the disk reappearing seconds later. In virtual machines it follows storage path failover, so check the host's multipathing before condemning anything in the guest. External drives that surprise-remove under load are usually a power problem, not a data one.
The fields that decide it
Everything else in the log line is context.
- Disk number
- Which disk went away, matching Disk Management's numbering. On a machine with one internal drive, disk 0 is the boot disk and this event naming it is serious.
- Whether it came back
- Not a field, but the thing to establish. A matching disk-arrival entry seconds later means an intermittent connection; no return means the device is gone until reboot.
- Timing against write activity
- Whether the removal happened during a backup, a copy, or an update. A surprise removal mid-write is how volumes end up needing chkdsk.
- Related NTFS events
- Whether Event 55 or 140 follows. That is the difference between an inconvenience and actual filesystem damage.
Common questions
Is Event 157 a problem if I unplugged a USB drive?
No. Windows logs a surprise removal whenever a disk disappears without being ejected first, and pulling a USB stick out is precisely that. It is only worth acting on if you were copying files at the time, in which case check the drive's contents, or if the disk it names is an internal one.
Event 157 names an internal drive I never touched. What now?
Something interrupted the connection while the machine was running. In order of likelihood: a loose or failing SATA or power cable, a failing drive, or a power supply that cannot hold up under load. Reseat both cables first — it is free and it is the answer more often than not. If it recurs, move the drive to a different port and cable before replacing anything.
Can Event 157 corrupt my files?
It can, and that is the real risk rather than the event itself. If the disk vanished while Windows was writing, the write did not complete. Look for NTFS Events 140 and 55 immediately afterwards; if they are there, run chkdsk on the volume. If nothing was being written at the time, there is usually no damage.
Why does Event 157 keep repeating on the same disk?
An intermittent connection — a cable that is nearly seated, a backplane slot with a poor contact, or a drive whose controller resets under thermal load. Each cycle shows as a removal and then an arrival. This pattern is more damaging over time than a single clean failure, because every cycle risks interrupting a write.
Read next
- Usually comes before Event 153: A disk read or write had to be retried I/O retries, which often appear for minutes before a marginal drive drops off entirely.
- Usually comes after Event 140: NTFS could not write to its transaction log NTFS failing to flush its transaction log, the usual immediate consequence of a volume vanishing mid-write.
- Usually comes after Event 55: NTFS found corruption on a volume Filesystem corruption discovered after the fact.
- Read alongside Event 129: A storage controller reset the drive Controller resets, which come from the same class of connection fault.
Mentioned by
Vendor documentation
Last reviewed 6 September 2026