Fix "This Add-In Could Not Be Started" Error in Microsoft Office
Question details
Office add-ins downloaded from AppSource fail to start in Word, Excel, and other Office applications.
- Product
- Microsoft Office
- Device & OS
- Windows 10
- Scenario
- Attempting to launch and use downloaded AppSource add-ins within Microsoft Office applications.
- Observed behavior
- The add-ins refuse to start, displaying a "This Add-In Could Not Be Started" error message even after repairing the software and installing updates.
Make sure that your Windows 10 system is fully updated, and temporarily disable any strict firewall or third-party antivirus software that might block Office applications from reaching Microsoft servers.
Run as Administrator and Modify ActiveX Settings
Adjusting the Trust Center settings and elevating application permissions ensures Office is allowed to run the necessary controls for the add-in.
Sometimes, strict security settings block active web controls or add-ins from loading correctly. Changing your ActiveX settings to provide a prompt rather than silently disabling controls usually resolves this error.
Close all running Office applications. Locate the shortcut for your specific application (e.g., Word or Excel), right-click it, and select "Run as administrator".
Open a blank document. Navigate to the "File" tab in the top-left corner, and click on "Options" at the bottom of the menu.
In the Options window, select "Trust Center" from the left-hand pane, then click the "Trust Center Settings" button.
Click on "ActiveX Settings" in the left menu. If "Disable all controls without notification" is currently selected, change it to "Prompt me before enabling all controls with minimal restrictions".
Click "OK" to save your new Trust Center settings. Completely close the Office application and relaunch it normally to test if the add-in starts.
Force a Manual Office Update
Verify and install any missing Microsoft Office updates that contain necessary patches for the AppSource framework.
Avoid Add-in Errors with WPS Office
If troubleshooting Microsoft Office add-in errors is slowing down your productivity, consider switching to WPS Office. It is a highly compatible, fast, and feature-rich free office suite that comes with essential tools built directly into the software, minimizing the need for third-party add-ins.
- 1. Download the Installer: Visit the official WPS website and download the free installer for Windows.
- 2. Install WPS Office: Run the setup file and follow the on-screen instructions to install the suite.
- 3. Open Your Documents: Launch WPS Office and instantly open your existing Word, Excel, or PowerPoint files with perfect formatting preservation.
Frequently Asked Questions
Why do AppSource add-ins fail to start even after repairing Office?
Repairing Office restores corrupted system files but does not reset customized security preferences. If your Trust Center settings are restricting ActiveX controls, the add-in will continue to be blocked until those settings are manually adjusted.
Does running Office as administrator pose a security risk?
Running an application as an administrator gives it elevated permissions to make system changes. While doing this temporarily to fix an add-in issue is safe, it is not recommended for daily use as it bypasses standard Windows security prompts.
Will these settings affect macros in my Excel workbooks?
ActiveX settings are distinct from Macro settings in the Trust Center. However, both control executable content. Modifying ActiveX settings to prompt you will not change how standard VBA macros operate in your workbooks.
