What is BAD-SEC-UNC?
Physically bad sectors found on disk is a high-severity storage drive (SSD/HDD) issue. The HDD surface or SSD memory cell has been permanently damaged. Common triggers are defective cable, power outages and high temperatures in the M.2 slot. Work through the steps below in order.
Common Causes
- End of life (age)
- Defective cable
- Power outages
- High temperatures in the M.2 slot
Step-by-Step Fix Guide
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1
Back up all data immediately
We'd suggest Back up all data immediately first — it's the fix most often responsible for solving BAD-SEC-UNC outright.
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2
Try replacing the SATA data cable
A recurrence usually points to a rarer storage instability cause, which is what the following steps are meant to catch.
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3
Run manufacturer diagnostics
Try "Run manufacturer diagnostics" next if the issue persists — it addresses a secondary cause.
Commands & Diagnostics
chkdsk C: /f /r
wmic diskdrive get status
Frequently Asked Questions
The leading cause of BAD-SEC-UNC is end of life (age), though defective cable, power outages and high temperatures in the M.2 slot also show up in our reports.
"Back up all data immediately" clears up most BAD-SEC-UNC reports by itself. The remaining steps above cover what's left.
BAD-SEC-UNC is a high-severity error. It won't damage your PC instantly, but repeated occurrences usually point to a deeper problem worth addressing soon.
You shouldn't need to. Work through the guide above first — a reinstall is only worth considering if none of those steps help.
Open CrystalDiskInfo (free tool) to check your drive's S.M.A.R.T. status. Any yellow or red indicators — especially reallocated sectors or pending sectors — confirm the drive is degrading and should be backed up and replaced immediately.
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