Where OST files are a cached copy of a message, keeping the original on the server, PST files may contain the only remaining copy of a message. These files are different than OST files. Warning: Be careful not to delete any PST files. Right-click the OST file and select Delete from the context menu. That way you can make sure you are deleting the correct file. While in the Folder Options dialog box it is also a good idea to deselect Hide extensions for known file types. To see this folder you will have to navigate to Folder Options > View tab > Show Hidden Files.

This means that deleting the OST file has zero implications, except maybe the wait as the cache rebuilds.įor Windows 7, 8 and 10 the OST file is typically located under the following in mind that AppData is a hidden folder. With an Exchange account, all your mail is actually stored on the Exchange server. So how do we fix a corrupt cache file? The simplest solution? Delete the cache file. Both technologies use caching to improve user experience. The difference with Outlook is that the cache is just one giant file versus the tens of thousands of tiny files your browser cache creates. A copy of all your emails is cached in a local file on your computer. Outlook caching works roughly the same way. Rather than fetching a new copy of a web page every time you visit a website your browser caches a copy of that web page instead. It works similarly to how the cache works in your web browser. The OST file is an offline cache of your Exchange mailbox. This error can also occur if you are using cached mode in Outlook and your OST file has become corrupt. You can repeat this process until you find the add-in preventing Outlook from starting Corrupt OST file To disable an add-in click the Go… button.įrom the Add-Ins dialog, you can deselect an add-in to disable it. From here you can see all add-ins that load when Outlook is opened in normal mode.

Furthermore, the reading pane and any toolbar customization will be disabled. Outlook will then launch with all add-ins disabled. You will receive a prompt asking whether you want to open Outlook in safe mode. To do this, hold the CTRL-key on your keyboard while clicking the Outlook icon. To determine if this is the root cause open outlook in Safe Mode. One possibility–and always the first thing to check–is that an Outlook add-in could be causing the error. The possible causes we cover in this article include: This error could occur for a number of different reasons. Windows will close the program and notify you if a solution is available. When launching Outlook you may receive the following error.Ī problem caused the program to stop working correctly.

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