The file username.ost is in use and cannot be accessed – Fixed

While visiting Microsoft’s support forum, we found that a number of users have reported the ‘The file username.ost is in use and cannot be accessed‘ error. Actually, an OST file is stored on your device, which is a duplicate copy of your mailboxes on the MS Exchange server.

Basically, due to the issues with your OST files, the mentioned error occurs. This post is going to provide a clear concept about why the error occurs and what the possible solutions are to fix this error in Outlook 2016. Stay with us on this post and keep reading.

Reasons why the error The file username.ost is in use and cannot be accessed occurs:

The glitch can happen for a variety of reasons, but it most frequently occurs whenever a user attempts to share, save, or send an MS Office document using programs like MS Word, PowerPoint, Excel, and so forth.

The error means that yet another process is using the Outlook OST file, and trying to close it may fix the situation. Many users, even so, will struggle to identify the specific software or procedure that is causing the error. The error also advises the user to perform a simple restart of the device, which generally fixes the problem.

However, there may be a number of other causes for the error, including such as:

• There may be a connectivity problem between both the OST and the corresponding Exchange inbox.
• MS Outlook conflicts with other functionalities.
• Attempts by numerous users to access the relatively similar OST file
• Inadequate internet integration
• Access permission to the OST file was not allowed.

Tips For Preventing and Resolving ‘Username.ost Is In Use and cannot be accessed’ error

In this main section, we will be discussing some methods that users can use to resolve this error and make OST data accessible for use. Basically, manual methods do not guarantee for the complete repair of the error that relates to the OST file. However, we believe you must try out these procedures before applying any professional solutions.

Run your Outlook in safe mode

This might be the most relevant and common fix that users can attempt to repair the error. It’ll just deactivate the defective Outlook add-ins or extensions that are causing problems with the Outlook functionality and its statistics. Therefore, execute your Outlook in the ‘safe mode’ and afterwards enter “outlook.exe/safe” into the empty command field (To execute the run functionality, tab Windows + R. You may consider it as a shortcut key.) wizard and simply tapping “OK”.

Afterward, in your Outlook program, go over to “Options” and select “Add-ins.” Select the “Go” option. Pick the add-ins that you believe are fundamentally flawed and then tap the “Remove” choice.

Deactivate the cached mode of MS Exchange

The “Cached Exchange Mode” enables MS Outlook users to collaborate offline. The above error can sometimes be resolved by partially or completely deactivating the cache mode in Outlook. Follow the instructions underneath to deactivate “Cached Exchange Mode.”

• Just after ending all MS Outlook functionality, navigate to “Control Panel.”
• Then, in the Control Panel, select “Mail,” and a new dialog box will automatically appear.
• Then choose “Email Accounts” from the opened dialog box, followed by “Email.”
• Choose the email account that is linked to Outlook and afterwards tap “Change“.
• Lastly, uncheck “Cached Exchange Mode” and click “Next” and then “Finish.”

Exit Outlook and end all relevant programs

Check that no multiple versions of Outlook are running on the same device and that no other related processes have access to the OST file. It can result in the OST file being labeled as ‘in use’. The stages are described.

• Shut down Outlook and launch the “Task Manager“.
• Choose the “Processes” icon.
• Take a glance at processes named “Outlook“, “LYNC”, “Communicator”, or “UCMAPI” in the lineup.
• Select this kind of mechanism and tap the “End Task” icon individually.

Fix your faulty OST file with scanOST

If all of the preceding methods mess up, then maybe the OST data file gets corrupted. Users could indeed fix the data files for MS Outlook editions lower than or equal to 2007 using the unlimited (free) default utility scanOST.exe.

It is a major constraint as the latest Outlook editions have been released, but you can use the scanPST.exe software to repair ost files in updated models of MS Outlook. Find the scanning process of scanOST as follows:

1. First, locate the scanOST tool in your device’s directory. If you are unaware of its location, then see the image as follows.
2. Then, start the built-in tool. This has classified the individual’s Outlook profiles; select the OST data file repair profile.
3. After that, for the OST error checking, pick the files or folders of the OST file.
4. Then specify the “Repair Errors” checkbox and, afterwards, tap the “Begin Scan” button.
5. The scanning will proceed and, when finished, will display a factual notice stating that the scan has been finished.

Use Professional tool to fix OST file is in use and cannot be accessed error

If the manual fixes don’t work, your OST file is probably corrupt or damaged. Regain OST Recovery Tool scans the damaged file, shows you a preview of the recovered data, and saves it in the format you choose, so you don’t lose your emails, contacts, or calendar items.

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Steps to Recover Data from a Corrupt OST File

1. Install and open Regain OST File Recovery on your computer.
2. Choose the corrupt or inaccessible OST file you want to recover.
3. The software scans the OST file for corruption or damage. Wait for the scan to finish.
4. Browse your emails, contacts, and other items to confirm everything you need was recovered.
5. Select the format you want, such as PST, EML, MSG, or MBOX, along with a destination folder.
6. You can keep the recovered data on your computer or migrate it to a cloud service such as Office 365 or Gmail.

FAQs

Q1. What does “The file username.ost is in use and cannot be accessed” mean?

Ans. It means another process or program is already using your Outlook OST file, so Outlook can’t open it. The error often appears when you try to save, share, or send a Microsoft Office document, or when the OST file has a problem.

Q2. What causes the “username.ost is in use” error in Outlook?

Ans. Common causes include a connection problem between the OST file and your Exchange mailbox, conflicts with other Outlook add-ins or functions, several users trying to access the same OST file, and missing access permissions on the file.

Q3. How do I fix the “username.ost is in use and cannot be accessed” error?

Ans. First, close Outlook and end related processes such as Outlook, Lync, Communicator, or UCMAPI in Task Manager. Then start Outlook in safe mode and remove faulty add-ins, or turn off Cached Exchange Mode. If none of these work, your OST file may be corrupt.

Q4. How do I start Outlook in safe mode?

Ans. Press Windows + R, type outlook.exe /safe, and click OK. Safe mode turns off add-ins that may be locking the OST file. Then go to Options > Add-ins, click Go, and remove any add-in that looks faulty.

Q5. Can scanPST or scanOST repair a corrupt OST file?

Ans. The built-in scanOST tool works only for Outlook 2007 and earlier. Newer Outlook versions don’t include it, and scanPST is designed for PST files, not OST files. For a corrupt OST file in a newer version, use a dedicated tool such as Regain OST Recovery.

Q6. How can I recover my emails if the OST file is corrupt?

Ans. If the error keeps coming back after the manual fixes, the OST file is likely damaged. Regain OST Recovery can recover your data from the corrupt file. You can download the free version to check how it works before you buy.