Symptoms

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When you open a file or send an email message in Microsoft Outlook 2010 or later versions, Outlook freezes, or you receive the following error message: 
Outlook not responding

Cause

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This problem occurs for one or more of the following reasons:
  • You have not installed the latest updates.
  • Outlook is in use by another process.
  • Outlook is loading external content, such as images in an email message.
  • A previously installed add-in is interfering with Outlook.
  • Your mailboxes are too large.
  • Your AppData folder is redirected to a network location.
  • You have to repair your Office programs.
  • Outlook data files have become corrupted or damaged.
  • Your installed antivirus software is outdated, or it conflicts with Outlook.
  • Your user profile has become corrupted.
  • Another program conflicts with Outlook.


Notes

  • This issue may occur for one or more of the reasons in this section. To fix this issue, you may have to follow the troubleshooting steps in the "Resolution" section.

  • Many of these items can be automatically checked by the Microsoft Support and Recovery Assistant (SaRA). To start the automated checks, follow these steps:

    1. Install the Outlook Advanced Diagnostics tool.
    2. Click Run when you are prompted by your browser.
    3. In the report that’s generated, review the items on the Issues found tab. For configuration details about Outlook, Windows, and you computer, review the settings on the Detailed View tab.

Next step

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If the information in this Knowledge Base article does not help resolve your problem in Outlook 2016, Outlook 2013 or Outlook 2010, see the following resources for more information: