How to Fix Outlook Error 0x80070021? [100% Results]

User Query: “When I attempt to backup or copy my PST file, MS Outlook throws error code 0x80070021 at me, which states that- The process cannot access the file because another process has locked a portion of a file. What should I do? I urgently need to create a backup of all my PST files as a precautionary measure against potential data loss. Please help!”

Outlook error 0x80070021 usually occurs when users try to copy, move, or backup Outlook data files [PST] & prompted with the “access denied” message. The error is mainly caused when Windows locks the PST file because it is currently in use by another application or process. If not resolved quickly, it can hamper the backup operations & data migration tasks.

Let’s understand all the possible causes & resolutions to fix Outlook error 0x80070021 permanently.

Common Symptoms of the Outlook Error 0x80070021

Go with the common signs that increase the chances of having this Outlook error:

• Unable to copy or move PST files.
• Access denied message prompted.
• Error while backing up Outlook data.
• The file cannot be accessed or modified.
• Outlook behaves normally, but file operations fail.

Reasons for Outlook Error 0x80070021: Core Ones

This error code pops up not only in Outlook but also in other Windows programs that run in the background, including programs like Skype, Google Calendar Sync, etc. Here are some core reasons that can help you to resolve Outlook error 0x80070021:

• Storage space limits exceed A large PST file is prone to file corruption; hence, it is recommended not to exceed the file size by 10 GB. If you have any PST files over 10 GB, then you should try splitting them into smaller parts.
• Outlook is running in the background Even after closing the Outlook application, it is still running in Task Manager.
• Add-in conflicts Third-party add-ins can continuously access the PST file.
• Cloud Sync tools [OneDrive, etc.] Sync tools usually lock files during the upload or synchronization process.
• Anti-virus or security software Real-time scanning may block file access temporarily, which can also cause the error.
• Windows Search Indexing The indexing service may lock the Outlook data file [PST] during scanning.
• Corrupt PST file It is also one of the main causes of having this error, as it also makes the file inaccessible.

How to Fix Error 0x80070021 in Microsoft Outlook? [All Working Ways]

The following section will help you with the most feasible approaches to resolve 0x80070021 error.

Way #1: Perform a Clean Boot using the Run dialogue box

Clean Boot is a little bit different from Safe Mode; in Clean Boot, Windows starts up in normal mode but without non-essential and non-Microsoft background applications or services. The steps to perform a clean boot are listed below:

1. Press Windows + R keys, in the edit box, enter msconfig, and click OK.
2. Click on the Startup tab > Open task manager.
3. Disable all the earlier Enabled processes. Close the Task Manager, one done.
   
4. Next, click on the Services tab > check the Hide all Microsoft services box > click Disable all > OK.
   
5. Next, you will get a pop-up message as shown below, click on Restart.
   

A clean boot allows you to start Windows with a minimum number of processes running; try copying the PST file. Holding down the Shift key while Windows boots can also prevent programs (that run at Boot) from running.

Note: In step 4, always check the Hide all Microsoft services box; otherwise, on rebooting, you might encounter boot errors.

Way #2: Close Outlook Running in the Background

If Outlook is running in the background, you can encounter the Outlook Error 0x80070021. To stop Outlook from running in the background, follow the steps outlined below:

1. Right-click the Taskbar > select Task Manager from the list.
   
2. Under the Processes tab, look for Microsoft Outlook > select MS Outlook > click on End task.
   

Way #3 Disable Windows Indexing Tool

The disabling indexing tool ensures that the Outlook search program isn’t indexing the files, causing active Outlook instances to pop up in the background. To disable it, follow the steps outlined below:

1. Launch Outlook > click on the File tab > Options. This will open the Outlook Options window. From the left pane, click on Add-ins > Click on Go.
   
2. In the COM Add-ins window, uncheck the Windows Search Email Indexer and click OK.

Way #4 Recoveryfix for Outlook PST Repair [Smart Approach]

If you are still getting Outlook error 0x80070021, it implies that your PST files might be damaged or corrupted. Using Outlook’s built-in ScanPST.exe tool, you can fix the corruption of the PST file manually, but at a minor level. Also, there is no data integrity with that approach.

Hence, it is always safe to go with the advanced solutions. Recoveryfix always comes forward to help users to overcome these tricky scenarios with its smart software. Outlook PST Repair is one of them that handles all levels of corruption very easily & provides accurate & structured results accordingly. The tool ensures 100 % data integrity & security with a zero data loss guarantee. The interactive graphical interface lets even the non-tech savvy users use the tool without any technical assistance.

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Avoid Outlook Error 0x80070021 with these Preventive Tips

Check out the basic guidelines that can help you to minimize the chances of error.

• Regularly backup Outlook data.
• Use the latest version of Outlook & Windows.
• Avoid storing PST files in cloud-synced folders.
• Always close Outlook before copying PST files.
• Disable unnecessary add-ins & optimize anti-virus settings.

Final Words to Fix Outlook Error 0x80070021

Till now, we have covered all the relevant approaches to fix Outlook error 0x80070021 during PST file backup. Here is the complete conclusion of the blog:

• Minor issues: Close Outlook, restart the system.
• Moderate issues: Disable Add-ins, pause sync tools.
• Advanced issues: Clean boot, antivirus exclusion.
• Severe Corruption: Use the Outlook PST repair tool.

FAQs

Q- Why does error 0x80070021 occur only during backup operations?

A- During backup, users try to access the PST file, which is still in use with other processes.

Q- Can network drives cause Outlook error 0x80070021?

A- Yes. Accessing PST files over network drives can lead to file locking conflicts.