Script Lab Error "This add-in could not be started"

Copper Contributor

I tried running the example user defined function (UDF) but it did not work. It used to work a while ago when I first installed the Script Lab add-in. The attached screenshots show the error message and the Windows event log in the Event Viewer app. Clicking "Restart" did not work. Any suggestions on what could be wrong or what else I could do to troubleshoot this? Thank you.





5 Replies


The error message "This add-in could not be started" with the error code 0x80004005 indicates a general error that can have various causes. Here are a few suggestions to troubleshoot the issue with Script Lab:

  1. Check prerequisites: Ensure that your version of Office/Excel is compatible with Script Lab. Script Lab requires Office 2016 or later, Excel Online, or Excel for iPad. Also, make sure that you have the latest updates installed for Office/Excel.
  2. Disable other add-ins: Temporarily disable any other add-ins or plugins you have installed in Excel. Conflicts between add-ins can sometimes cause issues. Restart Excel and try running Script Lab again.
  3. Reinstall Script Lab: Uninstall the Script Lab add-in from Excel and then reinstall it.
  4. Here is how:
    • Go to the "Insert" tab in Excel and click on "Get Add-ins" in the "Add-ins" group.
    • In the "Office Add-ins" dialog, go to the "My Add-ins" section.
    • Find Script Lab in the list and click on the "..." (ellipsis) button next to it.
    • Choose "Remove" to uninstall Script Lab.
    • Restart Excel and reinstall Script Lab by following the same steps.
    • Try running the example UDF after reinstalling Script Lab.
  5. Update Script Lab: Make sure you have the latest version of Script Lab installed. Visit the Script Lab website or the appropriate add-in store (such as the Microsoft AppSource) to check for any updates and install the latest version if available.
  6. Check security settings: Verify that your Excel security settings allow the execution of add-ins and custom functions. Go to the Excel options or settings and navigate to the "Trust Center" or "Security" section. Ensure that "Enable All Macros" or "Enable Custom Add-ins" is selected. Adjust the settings as needed and try running Script Lab again.
  7. Try on a different machine: If possible, test Script Lab on a different machine or with a different user account to see if the issue persists. This will help determine if the problem is specific to your environment.

If none of these suggestions resolve the issue, you can try reaching out to the Script Lab support team or the Microsoft Office support for further assistance. They may be able to provide more specific guidance based on your setup and the error message you encountered.

Note: It is always a good practice to exercise caution when installing add-ins and ensure that you are downloading them from trusted sources.

I hope one of these suggestions helps in resolving the issue with Script Lab.

The text and the steps are the result of various AI's put together.


My answers are voluntary and without guarantee!


Hope this will help you.



I tried all of your suggestions, including #7, but nothing worked. I also tried using the Office Logging tool below, but I was unable to interpret or guess the information in the log. 


I think I will need to contact the Script Lab team. Do you know how can I do this?


Thank you.


Script Lab was developed by the Microsoft Office team as an open-source project. Since it is an open-source project, it does not have a traditional support team. Instead, users typically seek help through GitHub repositories or community forums.

To contact the Script Lab community or find assistance, you can try the following:

  1. GitHub Repository: Script Lab's primary development and issue tracking take place on GitHub. You can visit the official Script Lab GitHub repository at and check the "Issues" section to see if anyone else has reported a similar problem or ask a new question if needed.

Please note that since Script Lab is an open-source project, the level of support might differ from traditional commercial software. However, many open-source communities are very active and helpful, and you might find valuable assistance there.

As my knowledge is based on information available up to September 2021, there might have been updates or changes related to Script Lab or its support channels. I recommend visiting the official Script Lab website, checking the Microsoft AppSource, or referring to other up-to-date resources to get the latest information and contact details. Remember that for general Microsoft Office-related issues, you can always reach out to Microsoft support directly for assistance.

Alternative UDF Solutions: If Script Lab still does not work, consider using native Excel functionality or alternative UDF solutions available through other add-ins or custom VBA code.

The text and the steps are the result of various AI's put together.


My answers are voluntary and without guarantee!


Hope this will help you.


To contact with Script Lab team you may here GitHub - OfficeDev/script-lab: Create, run and share your code directly from Office  (you may use office-js project as well, but above is more direct way.)

Initial information about the project is here Microsoft Garage: Script Lab - an Office add-in


As for the error itself main question do you have such error for other web add-ins (e.g. Advanced Formula Environment aka Excel Lab, whatever) or such error is specifically for Scrip Lab.


If you have an error for other add-ins as well it could depend on combination of many factors, I'd start from WebView2 if it installed correctly.


I believe you google around, just in case couple of links which could help

This add-in could not be started. Some users see this after switching to Edge WebView2 · Issue #2507...

Add-in could not be started error - Revenue Grid Knowledge Base

Error: ADD-IN ERROR 'This add-in could not be started. Close this dialog to ignore the problem or cl...



The error only occurs for "Custom Functions" samples in Script Lab. I tried "Comment" samples in Script Lab and those samples worked. The only difference is that "Custom Functions" samples are UDFs, while other samples are not UDFs.

I tried running using Excel web, and it worked. But I cannot limit myself to using Excel web since certain key functionalities in Excel are only available on the Desktop app.

I tried a full reinstall of Microsoft Office on my Desktop, and also ran a "repair" on WebView2, but the issue remains.