How to Fix Error – “Outlook Data File Access Denied OST?”

Summary: When access to the Outlook data file (.ost) is denied, Outlook stops working and access to the emails and mailbox data is lost. Outlook users sometimes encounter this problem when they try to access their Outlook account on Windows. In this guide, we’ve discussed a few workarounds that can help you fix the ‘Outlook file access is denied’ error and restore your Outlook account.

Outlook stores emails, contacts, attachments, calendar, notes, tasks, etc., in an Outlook data file. The Outlook data file could be OST or PST based on the email account type and Outlook version you have installed. Outlook 2010 and later versions store the Exchange, Office 365, Outlook.com, and IMAP email account data in OST or Offline Folder File. The OST file is stored in the User Profile folder under ‘AppData’ by default. However, users can change this location based on their specific requirements.  

But if the OST file is relocated incorrectly, it can lead to errors, such as:

C:\Users\…..\abc@xyz.com.ost.”

The File C:\Users\….\abc@xyz.com.ost cannot be opened.

These error messages may also appear due to several other reasons, such as:

• Damaged or inaccessible OST file
• Incorrect file permission or lack of administrator access to read/write the OST file
• Storage media issue
• Conflict with other applications accessing the OST file, such as Lync, Skype for Business, or antivirus tool
• Accessing the OST file with different Outlook profile
• Incompatible or faulty Add-ins
• Corrupt or damaged Outlook profile

The error indicates a problem with the OST file and requires an immediate fix to restore the Outlook account and prevent data loss.

TIP: To quickly fix the ‘file access denied’ error caused by inaccessible Outlook OST file, you can download and install Stellar Converter for OST. The software helps you convert the inaccessible or orphaned OST file to PST format, which you can import into your Outlook profile and restore the mail items with 100% integrity.

Solutions to Resolve Outlook OST File Access Denied Error

To solve the ‘file access is denied’ error in Outlook 2010, 2013, 2016, or 2019 on Windows, you can follow these solutions.

Solution 1: Check File Permissions

Incorrect or lack of file permission or ownership of the Outlook data file, i.e., OST, can prevent you from accessing the Outlook account as Outlook fails to access or read/write the OST file. To fix this, follow these steps:

• Open File Explorer and navigate to Outlook OST file location. If you don’t know the OST file location, refer to our guide to locate the OST file.
• Right-click on your Outlook OST data file and choose Properties.
• Click on the Security tab and click the Advanced button.
• Click Change and then click on the Enter the object name to select box (examples) box. Next, type your username and click the Check Names button.
• Select your username (or it will automatically fetch if there’s only 1 account matching your name) and then click OK.
• Under the Permissions tab, check ‘Full Control’ is mentioned under the ‘Access’ column beside your username. Click ‘OK.’
• Now sign out or restart the system and then open the MS Outlook.

If the error persists, head to the next solution.

Solution 2: Disable UAC or Run Outlook as Administrator

If the OST file is relocated or stored at a location that requires UAC (User Access Control) permission token, such as C:\Program Files\ or a similar location where you don’t have appropriate permission to perform this operation, it can also lead to the access denied error in Outlook.

However, this can be quickly resolved by running MS Outlook as administrator. For this, right-click on the MS Outlook application icon and then choose ‘Run as administrator.’

Alternatively, you may also disable the UAC to fix this error. However, disabling UAC is not recommended as it compromises the system security.

Solution 3: Relocate OST

If your organization has a policy that prevents them from providing you the admin access, you can relocate the OST file to a location that does not require UAC permission. You can use the ForceOSTPath registry key method to safely relocate or move the OST file to another location on your system drive, external storage, or network drive.

Solution 4: Close Conflicting Applications

Applications such as Lync and Skype for Business also access and store the information in OST data files. These applications may lock the OST file while storing the data, preventing MS Outlook from accessing the OST file. As a result, Outlook displays the file access is denied error.

Similarly, if the antivirus tool scans the system, it may also lock the OST file during the scan. To prevent such situations and resolve the OST file access denied error, you can close all the applications that may have access to your Outlook OST file. The steps are as follows:

• Right-click on the Taskbar and choose ‘Task Manager.’
• Click ‘More Details’ (skip if Task Manager is already displaying all the processes).
• Find and close the following processes:
  • Communicator
  • Lync
  • Ucmapi
  • Outlook
• Then open Outlook and check if the error is resolved. If not, try closing the antivirus software (if running).

You may also add an exception for OST files in antivirus software, if it’s the culprit behind the OST file access denied error. If this doesn’t resolve the error, follow the next solution.

Solution 5: Repair OST File

There could be a problem with the OST file which is preventing MS Outlook from reading or accessing it. For example, an OST file may get damaged or become inaccessible due to integrity issues caused by system crash, abrupt shutdown, force close, or large size.

However, Microsoft provides an Inbox Repair Tool (ScanPST.exe) to repair the OST file. The steps to repair the OST file are as follows:

• Close MS Outlook and launch ScanPST.exe, present in the Microsoft Office directory located in C:\Program Files\ or C:\Program Files (x86)\.
• Click ‘Browse’ to select the OST file and then click ‘Start.’
• If the tool finds errors in the OST file, click the ‘Repair’ button.
• After the repair, open Outlook and check if the error is resolved.

Note: ScanPST.exe can repair OST files with size up to 2 GB. Also, it can only fix minor issues with the OST file.

If the OST file is larger than 2 GB or ScanPST.exe fails to fix the issue, you can use an OST to PST converter software, such as Stellar Converter for OST to convert OST to Outlook importable PST format.

Solution 6: Disable Add-Ins

Incompatible or faulty add-ins could also lead to Outlook errors and may lead to inaccessible OST files. To fix this, you can find and disable the incompatible or faulty add-ins. The steps are as follows:

• Close Outlook and press ‘Windows’ + ‘R.’
• Type ‘Outlook /safe’ and press ‘Enter’ or click ‘OK.’ This will open the Outlook in Safe Mode.
• Click File > Options and then click ‘Add-ins.’
• At the bottom, click on the ‘Go’ button located beside Manage.
• Uncheck all the Add-Ins to disable them and click ‘OK.’  

• Restart the Outlook normally and check if the error is resolved.

If you are able to access the Outlook account and OST file, enable each add-in (one at a time) to find the faulty add-in and then remove it.

Solution 7: Create New Profile

It’s possible that the Outlook profile you are using may have got damaged or corrupted. This can prevent Outlook from accessing the OST file, which results in file access denied error. To solve this, you can create a new Outlook profile. The steps are as follows:

• Open the Control Panel, then select Large Icons in ‘View by:.’
• Find and click on the Mail option.
• Click the Show profiles tab and then click on Add to add a new profile.
• Enter your profile name and then press OK.
• Enter your name, login credentials, and other details, and then click Next.

Restart the Outlook application to check if the error is resolved. If not, head to the next solution.

Solution 8: Open OST with Authorized MAPI Profile

OST file is encrypted with MAPIEntryID GUID key and requires authentication from authorized MAPI profile. Thus, if you try to access or open an OST file from your Outlook profile that isn’t associated with the OST file, you may receive the file access denied error.

You can’t just access or open any OST file through other Outlook profiles. However, you can download and install Stellar Converter for OST if you need to access an OST file or extract mail items.

The software helps you extract and save the mail items from inaccessible, orphaned, or damaged OST files to PST format, which you can import into any Outlook profile.

Stellar Converter for OST can also help you restore the mail items from such inaccessible OST files directly to your Outlook profile or directly export to live Exchange mailbox or Office 365 account.

Wrapping Up

It’s difficult to find the exact reason behind the Outlook OST file access denied error as it may occur due to several reasons. Thus, you are required to apply various possible solutions to fix the error. In this post, we’ve described all possible solutions to fix the “Outlook OST file access is denied” error. You must follow these solutions in the given order of sequence to avoid issues. However, you can also use Stellar Converter for OST to quickly resolve the Outlook OST file errors and regain access to your mail items. The software helps you by converting the inaccessible OST file to Outlook importable PST format. Thus, you can reset your Outlook account without worrying about data loss. Once reset, configure a new profile in Outlook to fix the error and then import the converted PST file to regain access to all your mail items.