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.pst files are Microsoft Outlook's email and data storage containers. They can occasionally be damaged, but Microsoft Office includes a repair tool.

I am running Windows 7 and my Outlook has stopped working. It states that the folder that the .pst is in is damaged. I was hoping that you could provide me with a fix please and thanks. Error Message: Cannot start MS Outlook. Cannot open the Outlook window. The set of Folders cannot be opened. Errors have been detected in the file C:\Users\Avery\AppData\Local\Microsoft\Outlook\Outlook.pst

".pst" files are the container files used by Microsoft Office's Outlook email program to store all of your data. (Note that this is not Outlook Express, which is a different, unrelated program that I recommend that people stop using.)

When that file becomes corrupt for whatever reason, the potential for data loss is high. Fortunately, it doesn't happen often and being a single file makes it almost trivial to backup regularly.

But because it can happen, Microsoft includes a tool with Office to help repair your Outlook .pst file: scanpst.

Before you start

Before you run scanpst, you'll need to close Outlook if you have it running. Scanpst can't do its job if Outlook has the .pst file open at the same time.

After closing Outlook, I recommend making a backup of the .pst file. Because it's a single file, just copy it somewhere for safe keeping in case scanpst makes things worse or causes unexpected data loss (it's been known to happen.)

Locating scanpst

Scanpst, as its name implies, scans your .pst files for errors and repairs them if it can.

Even though you probably won't find it on any Start menu, scanpst should be included with your installation of Microsoft Office:

ScanPst.exe in the Microsoft Office 2010 installation

Here you can see ScanPst.exe in Windows Explorer where it's located in "C:\Program Files (x86)\Microsoft Office\Office14".

"Program Files (x86)" may be simply be "Program Files", depending on your version of Windows, and "Office14" may be some other number depending on your version of Microsoft Office (this example uses Office 2010 in Windows 7 64-bit).

Running scanpst

Double-click scanpst to run it.

Scanpst's interface is very simple:

Scanpst's interface

It only asks you for the location of the .pst file that you want to scan.

In your case, the error message told you exactly where to look: "C:\Users\Avery\AppData\Local\Microsoft\Outlook\Outlook.pst" and that's exactly what you would enter, or you could use the Browse button to locate the file.

In my example, my pst file is at "C:\Users\LeoN\Documents\Outlook Files\Outlook.pst".

After you've entered the .pst file location, click Start.

Scanpst results

If your .pst file is large, scanpst will take a while to perform its checks. If it finds any anomalies, it will prompt you before repairing them:

Scanpst reporting results

Even though you made a backup of the .pst file before we began, it's a good idea to let scanpst make another. You can never really have too many backups.

Click Repair and let scanpst do its thing.

After running scanpst

Assuming that all succeeds, you can now re-open Outlook and hopefully the errors will have been resolved.

If not or if you're at all curious, you'll also find a ".log" file in the same folder as your ".pst" file that may give you some clues as to what might be happening. Chances are that there will be a lot of technical gibberish, as .pst files are very complex, but as I said, perhaps there will be a useful clue.

Things to note

One of the most common causes of .pst corruption, and unfortunately data loss, is having an "old format" .pst (pre-Outlook 2003) that exceeds two gigabytes in size. Even though you may have upgraded Outlook itself, the file format may not have been automatically converted to a newer format capable of handing larger file sizes. If that happens to you, you'll need to upgrade the file format yourself.

In general, large .pst files are something to be avoided for a number of reasons. I do have a few hints for dealing with large pst files.

Unfortunately PST repair topics tend to be magnets for comment spam relating to third party tools that supposedly repair PSTs. As a result I'll have to reject any comment that looks like that kind of comment spam. If you're legitimately sharing a good experience - I apologize, please blame all the spammers - if you have a product you wish to promote, you can read up on advertising on Ask Leo!.

Article C4942 - September 30, 2011 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Larry G
October 4, 2011 8:10 AM

In the businees world a .pst file is perhaps the most important file for a person contrary to your statement that since it is a single file it is trivial if you loose data. That single file can contain all the email & data from many projects. Of all the files to backup that one should be #1 on the list.

October 4, 2011 10:25 AM

@Larry G, Leo did not say it was trivial if you lose the pst file, he said it was a trivial job to back it up. Completely different!
Try reading the article properly before you comment (as Leo suggests).

Roger PB
October 5, 2011 8:07 AM

I am running Windows 7 and MS Outlook 2007.
I cannot find scanpst.exe anywhere.
Your comments, please.

Roger PB
October 5, 2011 9:01 AM

Your article showed my outlook.pst was in a directory called C:\users\roger\appdata\local...
but I could not find an appdata directory in "My computer" even when I set it to show system files.
So I could not back it up. Nor could I find it when I used "search all files."
However, an option reached by right-clicking personal folders, is "open outlook data file". But this too has a hidden address,(local) and produces an error message if you try to copy it or send it elsewhere.
You blithely state that one should make a backup before using scanpst. But how?

You may need to have Windows Explorer configured to show system and hidden files. Those are two confusingly similar yet actually very different things.
October 5, 2011 2:34 PM

Microsoft has for year "hidden" like Larry G says, maybe the most important data file of all times.

I ALWAYS move that file to a location where I can easily track it, and where I easily can include it in regular backups (in my case, it is in a subfolder of "Documents").

Microsoft also has a nifty plug-in for Outlook that automatically prompts you - and does the work - of backing up your pst files when you shut down Outlook. Highly recommended add-on.

October 10, 2011 11:11 PM

Leo, in this article and at least one other, you have recommended against the most reliable e-mail program available, Outlook Express. I am writing this from a fairly speedy laptop with an i5-450 processor and 8 gigs of ram using Windows 7 Professional Edition. In order to download my e-mail quickly, I have to switch into Microsoft's Virtual XP. Virtual XP is slow, clunky, and an extra step I'd rather not take, but even so, by using Outlook Express in the virtual machine, I can still download my e-mail much quicker than I can using Thunderbird with Windows 7 in the non-virtual mode, and I'm pretty sure you could too. I have saved e-mail messages going back over ten years in Outlook Express, with never a lost message or any other glitch. Dropping Outlook Express was, in my opinion, one of the most user-unfriendly things Microsoft has done. I've tried at least seven other e-mail client programs that would run in Windows 7, and for ease of use, simplicity of interface, and just plain no-nonsense speed, none of them can touch Outlook Express. I don't have much hope that Microsoft will revive it with Windows 8, but it would sure be helpful if some smart developer would come up with a decent clone for it that would run under the newer operating systems.

You don't see what I see - based on questions to Ask Leo! more people lose email because of Outlook Express than any other email program I hear of. There are many reasons why I strongly advise moving away from it: Why Outlook Express Must Die
March 9, 2012 12:14 PM

I ran scanpst.exe as suggested. It reported no errors. Then I booted Outlook in safe mode and continue to get a "Databinding..." message at the bottom of the screen. Then a box opens that says the file is being checked for problems. Eventually, that box closes, but the program continues to be locked up (not responding) indefinitely. This loop is repeated endlessly.
I use Outlook for several email accounts including a hotmail POP file. Any suggestions would be much appreciated.

Chris Bailey
March 30, 2012 2:11 PM

IT WORKED!!!!! Thank goodness it worked!!!!! 2.3G of information almost lost. It took awhile to scan and repair but it was worth the wait. Your instructions here were easy to follow. Thank You!!

Jack Somana
May 2, 2012 2:37 PM

Hi Leo,

I might have a similar problem after my organisation moved from Office 2007 to 2010. Now suddenly I'm repairing pst's all over the place. This keeps coming back though as soon as users put\file any new emails into the pst's, as they go bust again. Maybe i had dodged a bullet since the pst's were created in Office 2003 and the pst's sizes has grown exponentialy as user's tend to use them as "dumping sites" as soon as they get the message that their mailboxes are full. Hope you can assist. God Speed.

Make sure that the PSTs are *created* using Office 2007 or later. Upgrading Office Outlook does not automatically upgrade the file format and older PSTs will break when the cross the 2 gigabyte size threshold.
May 24, 2012 10:38 PM

Leo, you are my hero. I was messing around trying to open Outlook 2007 all day; even uninstalled it and installed a trial version of 2010, and nothing. Then, I followed your instructions and my pst file was cured! Thanks! :)

N Selvam
June 5, 2012 8:46 AM

My PST file has this error when I ran SCANPST. An unknown error has occurred. Error Code 0X80004600. Outllook 2007. Appreciate your advice. Thank you in advance

June 9, 2012 9:57 AM

Thank you so very much! This worked for me first time! What a god send!

Sha Sykes
June 27, 2012 10:39 AM

Good day Leo, Thank you for the instructions. My laptop keep saying that it is not responding before it gets to finish the process; can you give me another alternative please to solving this problem for the corrupt .pst file? Thank you. Sha

August 8, 2012 8:11 PM

thanks a heap - a really handy tip

Marty W
August 17, 2012 10:09 AM

Leo: When running ScanPST.exe to repair a PST file, you should run the program 3 times in a row on the same file, or until it reports no more errors have been found. Even if it still shows errors, the program limits you to 3 runs on the file in one session.

Sarah Smith
November 22, 2012 12:41 AM

For applying pst file repair steps correctly through scanpst, it is necessary to identify the version of Outlook. These steps may differ from one version to another. You have stated good information about scanpst. Thanks for that !!. However, I have to say that we should not forget that this utility does not always solve the purpose of repairing the file. Thus keeping the backup is a safe option.


Yuhannes Watts
December 1, 2012 10:28 PM

Leo - many thx for this post, it got right to the point and helped me find the the inbox function in the correct folder.

February 27, 2013 6:54 PM

Thank you Leo. Even though I don't know much about computers your instructions were right on.
Again thank you very much.

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