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How to fix Outlook error 0x80070021?

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Microsoft updates Outlook for Web: 8 key features that make it better

Outlook is one of the more popular programs when it comes to email clients on Windows. However, as polished as the Outlook or the whole MS Office experience is, it can face bugs and glitches from time to time. 

In this article, we’re talking about the 0x80070021 error in Outlook, which happens while trying to copy files between two locations. 

Also read: How to create a group email in Outlook?

What causes the error 0x80070021?

There are several reasons why you may be facing this error. Here are some of the most common ones.

  • HTTP Activation not enabled: If you’re facing this issue while trying to host a WCF service in an empty ASP.NET application, disabled HTTP activation is most likely the cause of the error.
  • ASP.NET version is disabled: If the required ASP.NET version is disabled or not available on the host machine, you’ll get this error.
  • Outlook data conflict: If Outlook’s data is being used by another program, add-ins or spam filters, you’re likely to face this issue.
  • Search Email Indexer: There’s a problematic Outlook add-in called Search Email Indexer, known to cause 0x80070021 error if you’ve got it installed.
  • Lyns (MS Office Communicator) and Outlook conflicts: If you’ve got Lyns installed on your machine, it can prevent Outlook’s data files from being modified and hence trigger the error. 
  • Third-party conflicts with Outlook’s data files: Another likely reason for the error is a third-party program conflicting with Outlook over its data files.

Also read: How to add Bcc in Outlook?

How to fix error 0x80070021?

Here are ten ways you can resolve the Outlook error.

Enabling HTTP Activation from .NET Framework 4.5 Advanced Services

Aforementioned, if you’re getting this error while trying to host a WCF service in an empty ASF.NET application, the cause is likely HTTP activation.

Step 1: Press WIndows key + R to open the Run prompt. Type in appwiz.cpl and press enter.

Step 2: Click on Turn Windows features on or off in the left pane.

Step 3: In the features list, expand the .NET Framework Advanced Services of whichever version that you’re using followed by WCF Services.

Step 4: Check the HTTP Activation checkbox and click OK. 

Restart your PC and try again.

Enabling ASP.NET 4.5, 4.6, 4.7

If the 0x80070021 error occurs on an OS older than Windows 10 and in conjunction with IIS 8.5 or newer, you could resolve it by enabling ASP.NET.

Step 1: Press Windows key + R to open the Run prompt. Type in appwiz.cpl and press enter.

Step 2: Click on Turn Windows features on or off in the left pane.

Step 3: Expand the Internet Information Services folder and check the Word Wide Web services checkbox. 

Restart your PC and try again.

Closing Outlook using Task Manager

If you’re encountering the issue while trying to copy Outlook data files, ending the Outlook process from the Task Manager and restarting it can help resolve the issue. 

Step 1: Right-click the Taskbar and click on Task Manager.

Step 2: In the Processes tab, close all the running Outlook processes. 

Restart Outlook and try copying the files now. Note that some users have reported that closing Skype using the Task Manager also helped them resolved the issue, so you might want to give that a shot as well. 

Also read: How to add Grammarly to Microsoft Word and Outlook?

Uninstalling Search Email Indexer

Search Email Indexer is a problematic add-in that can cause Outlook error 0x80070021. Here’s how you can disable the add-in to resolve your issue, hopefully.

Step 1: Open Outlook and click on File.

Step 2: Click on Options.

Step 3: Head over to the Add-ins screenClick the drop-down menu under Manage. Then select COM Add-ins and click Go.

Search for Search Email Indexer and click Remove to uninstall the add-in. Restart your PC and give it another go.

Uninstall MS Office Communicator (Lyns)

Although Microsoft no longer supports this tool, it’s still installed on some user’s PCs and can conflict with Outlook’s data files, resulting in the 0x80070021 error. Here’s how to remove it from your PC.

Step 1: Press Windows key + R to open the Run prompt. Type in appwiz.cpl and press enter.

Step 2: Find Microsoft Office Communicator in the list and click the Uninstall button. 

Once the uninstallation is complete, restart your PC and give Outlook another shot.

Also read: What version of Outlook do I have?

Clean Booting Windows

A clean Windows boot with nothing else except Microsoft services can help you get around this Outlook error.

Step 1: Press Windows key + R to open the Run prompt. Type in msconfig and press enter. 

Step 2: Under the General tab, check Selective Startup and uncheck the Load startup items checkbox. 

Step 3: Now, head over to the Services tab and disable all non-Microsoft related services.

Now restart your PC and try Outlook again. 

Try Windows Safe Mode

Booting into the Windows Safe Mode can let you work around most Outlook problems, including 0x80070021 error.

Step 1: Press Windows key + R to open the Run prompt. Type in ms-settings:recovery and press enter. 

Step 2: Click Restart now under Advanced startup.

Step 3: Once your PC boots up again, head over to Troubleshoot, followed by Advanced Options and click on Startup Settings. 

Step 4: Press either the F4 or the key to boot into the Safe Mode.

Now try the operation you were trying before, and it should happen without any glitches. 

Also read: How to fix the ‘Outlook Cannot Expand folder’ error?

Yadullah Abidi

Yadullah Abidi

Yadullah is a Computer Science graduate who writes/edits/shoots/codes all things cybersecurity, gaming, and tech hardware. When he's not, he streams himself racing virtual cars. He's been writing and reporting on tech and cybersecurity with websites like Candid.Technology and MakeUseOf since 2018. You can contact him here: