Troubleshoot user errors with Office Add-ins

At times your users might encounter issues with Office Add-ins that you develop. For example, an add-in fails to load or is inaccessible. Use the information in this article to help resolve common issues that your users encounter with your Office Add-in.

You can also use Fiddler to identify and debug issues with your add-ins.

Common errors and troubleshooting steps

The following table lists common error messages that users might encounter and steps that your users can take to resolve the errors.

Error message Resolution
App error: Catalog could not be reached Verify firewall settings."Catalog" refers to AppSource. This message indicates that the user cannot access AppSource.
APP ERROR: This app could not be started. Close this dialog to ignore the problem or click "Restart" to try again. Verify that the latest Office updates are installed, or download the update for Office 2013.
Error: Object doesn't support property or method 'defineProperty' Confirm that Internet Explorer is not running in Compatibility Mode. Go to Tools > Compatibility View Settings.
Sorry, we couldn't load the app because your browser version is not supported. Click here for a list of supported browser versions. Make sure that the browser supports HTML5 local storage, or reset your Internet Explorer settings. For information about supported browsers, see Requirements for running Office Add-ins.

When installing an add-in, you see "Error loading add-in" in the status bar

  1. Close Office.
  2. Verify that the manifest is valid
  3. Restart the add-in
  4. Install the add-in again.

You can also give us feedback: if using Excel on Windows or Mac, you can report feedback to the Office extensibility team directly from Excel. To do this, select File | Feedback | Send a Frown. Sending a frown provides the necessary logs to understand the issue.

Outlook add-in doesn't work correctly

If an Outlook add-in running on Windows and using Internet Explorer is not working correctly, try turning on script debugging in Internet Explorer.

  • Go to Tools > Internet Options > Advanced.

  • Under Browsing, uncheck Disable script debugging (Internet Explorer) and Disable script debugging (Other).

We recommend that you uncheck these settings only to troubleshoot the issue. If you leave them unchecked, you will get prompts when you browse. After the issue is resolved, check Disable script debugging (Internet Explorer) and Disable script debugging (Other) again.

Add-in doesn't activate in Office 2013

If the add-in doesn't activate when the user performs the following steps:

  1. Signs in with their Microsoft account in Office 2013.

  2. Enables two-step verification for their Microsoft account.

  3. Verifies their identity when prompted when they try to insert an add-in.

Verify that the latest Office updates are installed, or download the update for Office 2013.

Add-in doesn't load in task pane or other issues with the add-in manifest

See Validate an Office Add-in's manifest and Debug your add-in with runtime logging to debug add-in manifest issues.

Add-in dialog box cannot be displayed

When using an Office Add-in, the user is asked to allow a dialog box to be displayed. The user chooses Allow, and the following error message occurs:

"The security settings in your browser prevent us from creating a dialog box. Try a different browser, or configure your browser so that [URL] and the domain shown in your address bar are in the same security zone."

A screen shot of the dialog box error message

Affected browsers Affected platforms
Internet Explorer, Microsoft Edge Office on the web

To resolve the issue, end users or administrators can add the domain of the add-in to the list of trusted sites in Internet Explorer. Use the same procedure whether you're using the Internet Explorer or Microsoft Edge browser.


Do not add the URL for an add-in to your list of trusted sites if you don't trust the add-in.

To add a URL to your list of trusted sites:

  1. In Control Panel, go to Internet options > Security.
  2. Select the Trusted sites zone, and choose Sites.
  3. Enter the URL that appears in the error message, and choose Add.
  4. Try to use the add-in again. If the problem persists, verify the settings for the other security zones and ensure that the add-in domain is in the same zone as the URL that is displayed in the address bar of the Office application.

This issue occurs when the Dialog API is used in pop-up mode. To prevent this issue from occurring, use the displayInFrame flag. This requires that your page support display within an iframe. The following example shows how to use the flag.

Office.context.ui.displayDialogAsync(startAddress, {displayInIFrame:true}, callback);

Changes to add-in commands including ribbon buttons and menu items do not take effect

If changes you've made in the manifest, such as file names of ribbon button icons or text of menu items, do not seem to take effect, try clearing the Office cache on your computer.

For Windows:

Delete the contents of the folder %LOCALAPPDATA%\Microsoft\Office\16.0\Wef\.

For Mac:

Add-ins are often cached in Office for Mac, for performance reasons. Normally, the cache is cleared by reloading the add-in. If more than one add-in exists in the same document, the process of automatically clearing the cache on reload might not be reliable.

You can clear the cache by using the personality menu of any task pane add-in.

  • Choose the personality menu. Then choose Clear Web Cache.


    You must run macOS version 10.13.6 or later to see the personality menu.

    Screen shot of clear web cache option on personality menu.

You can also clear the cache manually by deleting the contents of the ~/Library/Containers/com.Microsoft.OsfWebHost/Data/ folder.


If that folder doesn't exist, check for the following folders and if found, delete the contents of the folder:

  • ~/Library/Containers/{host}/Data/Library/Caches/ where {host} is the Office host (e.g., Excel)
  • ~/Library/Containers/{host}/Data/Library/Application Support/Microsoft/Office/16.0/Wef/ where {host} is the Office host (e.g., Excel)

For iOS:

Call window.location.reload(true) from JavaScript in the add-in to force a reload. Alternatively, you can reinstall Office.

Changes to static files, such as JavaScript, HTML, and CSS do not take effect

The browser may be caching these files. To prevent this, turn off client-side caching when developing. The details will depend on what kind of server you are using. In most cases, it involves adding certain headers to the HTTP Responses. We suggest the following set:

  • Cache-Control: "private, no-cache, no-store"
  • Pragma: "no-cache"
  • Expires: "-1"

For an example of doing this in an Node.JS Express server, see this app.js file. For an example in an ASP.NET project, see this cshtml file.

If your add-in is hosted in Internet Information Server (IIS), you could also add the following to the web.config.

    <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="0.00:00:00" cacheControlCustom="must-revalidate" />

If these steps don't seem to work at first, you may need to clear the browser's cache. Do this through the UI of the browser. Sometimes the Edge cache isn't successfully cleared when you try to clear it in the Edge UI. If that happens, run the following command in a Windows Command Prompt.

del /s /f /q %LOCALAPPDATA%\Packages\Microsoft.Win32WebViewHost_cw5n1h2txyewy\AC\#!123\INetCache\

See also