How to Repair Outlook with the Inbox Repair Tool (scanpst.exe)
When Outlook won’t open, crashes on launch, freezes, or shows missing or garbled items and errors that mention your .pst or .ost file, the culprit is usually a corrupt data file — and the built-in fix is scanpst.exe, the Inbox Repair Tool. It scans an Outlook data file, repairs structural errors, and rebuilds the internal index so Outlook can read it again. It ships free with every classic Outlook install; you just have to find it and point it at the right file.
One important caveat up front: New Outlook for Windows does not use .pst/.ost files, so scanpst doesn’t apply there — skip to the New Outlook section for that fix.
What scanpst.exe Does (and When to Use It)
The Inbox Repair Tool checks the file structure of an Outlook data file and corrects errors it finds. It does not touch the Exchange/server copy of your mail — it repairs the local file. Reach for it when you see:
- Outlook won’t start, hangs on “Loading Profile,” or crashes repeatedly.
- Errors referencing the data file: “The file outlook.ost/.pst cannot be opened”, “errors have been detected in the file…”, or “Outlook data file cannot be accessed.”
- Missing, duplicated, or corrupt items — folders that won’t expand, emails that won’t open.
- Outlook is slow or freezes when opening a particular folder.
Two file types it works on:
.pst— a Personal Storage Table, used for POP/IMAP accounts, archives, and exported mail. This is your data; if it’s lost, it’s lost..ost— an Offline Storage Table, a cached copy of an Exchange/Microsoft 365 mailbox. Because it’s just a cache, a badly damaged.ostcan often be deleted and rebuilt from the server instead of repaired (Outlook recreates it on next launch).
Step 1 — Close Outlook Completely
scanpst can’t touch a file Outlook has open.
- Quit Outlook.
- Press Ctrl+Shift+Esc to open Task Manager.
- On the Processes tab, look for Microsoft Outlook / OUTLOOK.EXE. If it’s still listed, right-click it and choose End task.
Step 2 — Find scanpst.exe for Your Office Version
scanpst.exe lives in the Office program folder, and the exact path depends on your Office version, whether it’s Click-to-Run or MSI, and 32- vs 64-bit. The fastest method: open the Start menu or File Explorer search and type scanpst — Windows usually finds it. If not, check these paths (the Office16 folder name covers Office 2016, 2019, 2021, 2024, and Microsoft 365):
| Install type | Typical path |
|---|---|
| Microsoft 365 / Office 2016–2024 (Click-to-Run) | C:\Program Files\Microsoft Office\root\Office16\ |
| Office 2016–2024, 64-bit MSI | C:\Program Files\Microsoft Office\Office16\ |
| Office 2016–2024, 32-bit MSI on 64-bit Windows | C:\Program Files (x86)\Microsoft Office\Office16\ |
| Office 2013 | …\Office15\ |
| Office 2010 | …\Office14\ |
If File Explorer search doesn’t surface it, browse to the folder above and scroll to SCANPST.EXE. Double-click it to launch the Inbox Repair Tool.
Tip: Don’t confuse scanpst.exe with scanost.exe. Microsoft retired the separate OST scanner years ago — modern scanpst repairs both
.pstand.ostfiles.
Step 3 — Locate Your .pst or .ost File
You need the full path of the file to repair:
- In Outlook (if it opens), go to File > Account Settings > Account Settings.
- Click the Data Files tab.
- Each account’s data file is listed with its location. Click Open File Location to jump to the folder, or note the path.
If Outlook won’t open at all, the default location is usually:
C:\Users\<you>\AppData\Local\Microsoft\Outlook\That’s where .ost files and many .pst files live. (AppData is hidden — enable Hidden items in File Explorer’s View menu, or paste %localappdata%\Microsoft\Outlook into the address bar.)
Step 4 — Browse to the File and Start the Scan
- In the Microsoft Outlook Inbox Repair Tool window, click Browse.
- Navigate to your
.pstor.ostfile and select it. - Click Start.
scanpst runs up to eight passes, analyzing folders and items for inconsistencies. On a large file this can take a while — let it finish. When it’s done, it reports whether errors were found.
Step 5 — Back Up, Then Repair
If scanpst finds errors:
- Tick “Make a backup of scanned file before repairing.” This is important — keep it on.
- Confirm or change the backup location (it defaults to the same folder with a
.bakextension). - Click Repair.
The tool rewrites the corrected file and keeps your .bak copy as a safety net. If a repair ever makes things worse, you can rename the .bak back to .pst to restore the pre-repair state.
Step 6 — Reopen Outlook and Re-run if Needed
- Restart Outlook and check whether the issue is resolved.
- Run scanpst again if problems persist. Heavily corrupted files often need several passes — keep running it until it reports no errors found.
- If Outlook still misbehaves on an
.ost, close Outlook, rename or delete the.ost(e.g., tooutlook.ost.old), and reopen Outlook — it rebuilds a fresh cached copy from the server. Don’t do this with a.pst, which holds the only copy of your data.
Tip: If repaired items are missing afterward, look for a Recovered Personal Folders / Lost and Found folder in your folder list — scanpst places salvageable orphaned items there.
New Outlook for Windows: scanpst Doesn’t Apply
New Outlook for Windows stores nothing in .pst/.ost files. It’s an account-synced, cloud-backed client — your mail lives on the server and New Outlook keeps a managed local cache it controls. There’s no data file to point scanpst at, and the Inbox Repair Tool isn’t part of it.
If New Outlook is crashing, missing mail, or won’t sync, the equivalent “repair” steps are:
- Remove and re-add the account: Settings > Accounts > Email accounts > select the account > Manage / Remove, then add it back. This forces a clean resync from the server.
- Reset/repair the app: Windows Settings > Apps > Installed apps > Outlook (new) > Advanced options > Repair, then Reset if repair doesn’t help.
- Toggle back to classic Outlook temporarily if you need scanpst for an old archive
.pst— classic Outlook can still open and repair those files.
Troubleshooting
scanpst.exe not found
Search scanpst from the Start menu first. If nothing turns up, browse the version paths above — note that Click-to-Run installs hide it under …\root\Office16\, not the plain Office16 folder. If it’s genuinely missing, run an Office Quick Repair (Settings > Apps > Microsoft 365 > Modify > Quick Repair) to restore it.
scanpst hangs or won’t finish
Very large or severely damaged files can stall. Let it run (it can take a long time on multi-GB files), and make sure Outlook is fully closed. If it freezes mid-pass, close it, restart, and run it again — and confirm you have free disk space at least the size of the data file for the backup.
scanpst says it can’t repair the file
The corruption is beyond what the built-in tool handles. Restore the file from a backup if you have one, rebuild the .ost from the server (delete and let Outlook re-download), or for a critical .pst, try a third-party PST recovery tool. Always work on a copy.
Should I repair the .ost or the .pst?
Repair a .pst — it’s the only copy of that data. For an .ost, repairing works, but deleting it and letting Outlook rebuild from the server is usually faster and cleaner since it’s just a cache.
scanpst keeps finding errors every time I run it
Run it repeatedly until it reports zero errors — multiple passes are normal for badly damaged files. If it never reaches a clean result, the file is too corrupt for scanpst; move to a backup or a dedicated recovery tool.
Quick Reference
| Situation | Action |
|---|---|
| Outlook crashes / won’t open (classic) | Close Outlook, run scanpst.exe on the data file |
| Find the tool | Search scanpst, or C:\Program Files\Microsoft Office\root\Office16\ |
| Find your data file | File > Account Settings > Account Settings > Data Files |
| Corrupt .pst | Repair with scanpst (keep the backup) |
| Corrupt .ost | Repair, or delete and let Outlook rebuild from server |
| New Outlook problems | Remove/re-add account, or Repair/Reset the app (no scanpst) |
Fewer Crashes to Recover From in the First Place
scanpst is a last resort for when your local mail file goes bad — a problem that mostly exists because so much email work lives trapped in one fragile desktop client. Carly is an AI assistant that works over email and handles the heavy lifting — triaging, drafting, scheduling, and following up — from the cloud, so your workflow doesn’t hinge on one machine’s data file staying healthy. Carly connects to 200+ apps and starts at $35/month.
More on Outlook: How to back up Outlook emails · How to recover deleted emails in Outlook · How to clean up your inbox in Outlook · How to create rules in Outlook · How to fix Outlook search not working · How to filter emails in Outlook
Ready to automate your busywork?
Carly schedules, researches, and briefs you—so you can focus on what matters.
See what people say
"Before Carly, I relied on a Calendly link, but the whole process felt impersonal and not very professional. Carly changed that by handling all the back-and-forth, so I'm no longer stuck in endless email threads trying to line up schedules.
Now Carly reaches out to candidates, shares my real-time availability, lets them pick a slot, then sends a Zoom link and drops it straight into my calendar. She sends reminders to both of us before each call, which has significantly reduced no-shows and last-minute confusion.
On top of scheduling, Carly acts like a full executive assistant, sending me my schedule the night before so I can prepare for each call. It reminds me of the old x.ai assistant, but Carly is noticeably smarter, faster, and better suited to my healthcare recruitment business."
