Quick answer (for people who've done this before)
Open Control Panel > Indexing Options > Advanced, hit Rebuild. Wait for it to finish (could take hours). If that fails, delete the index files manually from C:\ProgramData\Microsoft\Search and restart the Windows Search service.
Why this happens
Windows Search uses a database file (Windows.edb) that gets corrupted when:
- Your drive runs out of space mid-indexing
- You force-shut down while the indexer is writing
- A third-party app (looking at you, old Adobe updaters) locks the file
- The index file grows past 4GB on a 32-bit system (rare now, but still possible on old builds)
I had a client last month whose Outlook search simply stopped working. Every query returned zero results. The index was sitting at 3.8GB and had a dozen file locks on it. Rebuild fixed it in 20 minutes, but the real problem was a dying hard drive. Point is — corruption is often a symptom, not the root cause.
Step-by-step fix: Rebuild the index
- Open Indexing Options. Press Win+R, type
control /name Microsoft.IndexingOptions, hit Enter. - Click Advanced. You'll need admin rights. If UAC prompts, click Yes.
- Click Rebuild. It will warn you this might take a while. It's not kidding — for a 1TB drive with 500K files, expect 2-4 hours. For a typical business workstation, 30-60 minutes.
- Wait. Don't close the window. Open Task Manager, look for SearchIndexer.exe. If CPU sits at 0%, something's stuck. If it's pegged at 100%, it's working.
- Test search. After the rebuild finishes, try searching for a file you know exists. If it works, you're done.
Alternative fix: Manual deletion (when rebuild fails)
If the rebuild button does nothing or errors out, the index file is too broken to repair. You'll nuke it manually.
- Stop the Windows Search service. Open Command Prompt as admin, run:
net stop wsearch - Delete the index files. Navigate to
C:\ProgramData\Microsoft\Search. Delete everything inside that folder. Don't worry — Windows will recreate it. - Restart the service. In the same command prompt, run:
net start wsearch - Force a reindex. Go back to Indexing Options, click Advanced, click Rebuild. This time it should work because the corrupt file is gone.
Alternative fix: Reset indexing locations
Sometimes the corruption is tied to a specific folder. For example, a massive Outlook PST file can bloat the index endlessly.
- Open Indexing Options.
- Click Modify.
- Uncheck everything except Start Menu and Users (or whatever you actually need).
- Click OK, then wait for the index to shrink. Then re-add locations one by one, testing search after each addition.
Prevention tip
Don't let your drive fill up past 80% capacity. Windows Search needs breathing room to write its database. I've seen corruption spike on drives with under 10GB free. Also, avoid indexing network drives — they cause constant lock conflicts. If you absolutely must index a network path, map it to a drive letter and add that drive to the index — but be warned, it's flaky.
One more thing: if you're on a laptop that frequently goes to sleep, disable indexing on battery. It'll save your index from mid-write corruption. In Power Options, set the hard disk to never turn off while on battery if you're actively indexing.
Real talk: search index corruption is one of those problems that feels like a hardware failure but isn't. If you rebuild and it still breaks within a week, test your RAM with MemTest86. Bad memory corrupts indexes like crazy.