How to Resolve Outlook 0x80070021 Error While Backing Up PST File

Microsoft Outlook is easily one of the best email clients, which does more than just send or receive emails. It is also used to perform tasks, take down notes, maintain calendar, journals and so on.

Like any other application or product, errors do exist in Outlook making the file inaccessible.

One such error is the 0x80070021 error. It occurs when you try to copy or backup your PST file to another location.

The error message reads: “The process cannot access the file because another process has blocked a portion of the file”.

One of the causes of this problem might be Outlook or any software that uses some features of Outlook is running in the background. Applications like Skype, Google Calendar Sync, Microsoft Office Communicator could be the culprits.

How to fix Outlook 0x80070021 error?

Fix 1: End Outlook Process with Task Manager

  • Press Ctrl + Alt +Delete to open Task Manager.
  • Under Processes tab, look for applications such as Outlook.exe or other applications using Outlook features.
  • Right-click on the process and select End process.

Fix 2: Fix Outlook error 0x80070021 using System Restore

  • Log into your system as an Administrator.
  • Click Start -> All Programs -> Accessories -> System Tools -> System Restoresystem restore
  • Now select “Restore my computer to an earlier time”
  • Under the option, “On this list, click a restore point”, select the latest system restore option and click Next.
  • Click Next on confirmation window.
  • Restart the system when restoration process is complete.

Fix 3: Repair MS Outlook Error 0x80070021 by Uninstalling Search Email Indexer

The COM Add-in, which may prevent Outlook from closing completely, is another cause of the error 0x80070021 the process cannot access the file. In other words, it forces Outlook to leave a background process running even after the application is closed. The conflict that causes the error code 0x80070021 can be resolved by uninstalling the COM Add-in.

  • Open Outlook application and click Fileoutlook file
  • Then choose Options from the vertical menu. outlook options
  • Select the Add-ins  outlook addins
  • Go to the bottom section of the screen and click on the drop-down menu associated with Manage.
  • Select COM Add-ins and click Go to see the list of installed Add-ins.
  • Select the Search Email Indexer and click on Remove to get rid of i

Fix 4: Fix for MS Outlook Error 0x80070021 Using Remo Repair Outlook

As we discussed before this error usually occurs when you are trying to copy or backup your PST file to another location. With all the above mentioned methods you should be able to fix the Outlook error 0x80070021. However, if you are still facing this error, making use of the Remo Repair for Outlook PST is an effective way to solve this problem. The software can repair the PST file and create a healthy PST file which can be used as a backup Outlook data file.

Remo Recover for windows

  • Download and install the latest version of Remo Repair Outlook software on your system.
  • On the home screen, select the option from Select the PST file Manually, Open Default PST File, Find PST file to select your corrupt PST file.  remo repair outlook
  • Now select Normal Scan. Select a destination path where you want to save the folder by clicking on Browse. Click Nextrepair pst outlook
  • Click on Repair to start the repair process.
  • Once the repair process is complete, you can view the repaired files through Preview
  • You can then view all the repaired files in your destination folder.

One of the best things about Remo Repair Outlook is the fact that you can repair password protected, oversized as well as compressed PST files.

The PST repair software works for all versions of Outlook including Outlook 2021 on all versions of Windows OS including the latest Windows 11.

Few users have also complained about losing folders on their Outlook application. These folders could contain important information and it is critical to restoring them as soon as possible.

Note: If you are interested in how to find lost Outlook folders, then go through the article.


Hope this article was helpful in fixing the error 0x80070021 on Outlook. It is recommended to make use of the tool by Remo Repair Outlook PST to fix any issues related to Outlook. Let us know your thoughts or queries in the comment section.

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