FIX: Outlook error 0x80070021

Matthew Adams
by Matthew Adams
Windows & Software Expert
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  • Microsoft is one of the most popular email clients on the market today.
  • Given its importance, we will be showing you how to fix Outlook error 0x80070021.
  • To learn more about this amazing tool, check out our dedicated Outlook Mail section.
  • We also have a dedicated Fix page for this tool alone as well.
Outlook error 0x80070021

Error 0x80070021 arises for some users when they try to copy (or back up) Outlook’s PST file to another folder. One user said this in a forum post:

When I attempt to backup/copy my outlook.pst file to another location I get error 0x80070021 the process cannot copy the file as another process has locked a portion of the file.

As a consequence, users can’t copy PST files to other folders.


How do I fix Outlook error 0x80070021?

1. Check Outlook isn’t running

Error 0x80070021 usually arises when MS Outlook, or another program associated with it, is running in the background when users try to copy their PST files.

  1. To check if Outlook is running, right-click your taskbar to select Task Manager.
  2. Select the Processes tab.
    Task Manager Error 0x80070021
  3. Select Outlook if it’s listed under Apps, and press the End task button.
  4. If Outlook isn’t listed under Apps, look through Background processes to check if it’s listed there.
    • If you find an Outlook background process there, right-click it and select End task.
  5. Some users have also confirmed that closing Skype via Task Manager fixes error 0x80070021.
    • So, repeat the above steps for the Skype app.

2. Uninstall MS Office Communicator

Error 0x80070021 can also be due to the virtually obsolete MS Office Communicator application conflicting with more recent Office software, such as Outlook.

  1. To uninstall MS Office Communicator app, press the Windows key + R.
  2. You can open the uninstaller window by entering appwiz.cpl in Run and clicking OK.
    Programs and Features applet Error 0x80070021
  3. If MS Office Communicator is listed in Programs and Features, select that software.
  4. Click Uninstall to remove Office Communicator.
  5. Restart Windows after uninstalling Office Communicator.

3. Clean Boot Windows

Clean-booting Windows will restart the platform with minimal background software and services, which might fix error 0x80070021.

  1. Open Run, which you can do with the Windows key + R keyboard shortcut.
  2. Input msconfig in Run and press Enter to open the window shown directly below.
    The General tab Error 0x80070021
  3. Click the Selective startup option on the General tab.
  4. Deselect the Load startup items check box.
  5. Select the Load system services and Use original boot configuration settings.
  6. Make sure the Hide all Microsoft services option is selected on the Services tab.
    The Services tab Error 0x80070021
  7. Then click Disable all to deselect all the third-party services.
  8. Click Apply, OK, and then Restart on the dialog box that opens.
  9. Thereafter, copy the Outlook PST after clean booting.
    • Then you can restore your original startup configuration.

Tired of frequent Outlook issues? Check out this article for some alternative email clients.


4. Restart Windows in Safe Mode

Try copying Outlook’s PST in safe mode.

  1. To do that, hold the Shift key and click Restart on Windows 10’s Start menu.
    The Restart option Error 0x80070021
  2. After restarting, select Troubleshoot > Advanced options > See more recovery options > Startup Settings.
    The Startup Settings option Error 0x80070021
  3. Click the Restart button.
  4. When the Startup Settings list appears, press the 4 key to select Enable Safe Mode.

5. Remove Outlook’s Search Email Indexer add-in

Some users have reputedly fixed error 0x80070021 by removing Outlook’s Search Email Indexer add-in, which keeps the application running with a background process.

  1. To remove that add-in, click File in Outlook.
  2. Click Options to open the options window.
  3. Click Add-ins on the left of the window.
  4. Select Com Add-ins on the Manage drop-down menu, and click the Go button.
    Outlook Options window Error 0x80070021
  5. Select the Search Email Indexer add-in, and click the Remove button.

Those are some of the confirmed resolutions for error 0x80070021 that have fixed the issue for Outlook users.

So, the resolutions above will usually fix the error. Aside from those fixes, rolling Windows 10 back to a restore point might also resolve the issue.

Let us know what troubleshooting steps did you use to fix this Outlook issue. Do so by leaving us a message in the comments section below.


FAQ: Learn more about Outlook

  • Is Outlook the best email client?

While Outlook is indeed a very solid email client, it would be hard to classify it as the best, given all of the available alternatives.

  • What can I use Outlook for?

Besides being a very good email client, Outlook is a very good personal information manager.

  • I can’t install Outlook on my PC. What can I do?

If no fix can help you install Outlook, you can choose to use the web client.