Troubleshooting: VSTO Add-In Not Visible in the Excel Ribbon?

Whether you’re a developer troubleshooting your VSTO (Visual Studio Tools for Office) add-in or a user trying to figure out why your custom tab isn’t appearing in Excel’s Ribbon, the issue of a “VSTO add-in not visible in Excel’s Ribbon” can be confusing. In this post, we’ll explore the most common causes of this problem and provide solutions to help both developers and users get the add-in working properly.

1. Restart Excel

When your VSTO add-in not visible in Excel’s Ribbon and Excel was open during installation, the tab might not appear. Close all instances and restart Excel.

2. Enable the Tab

Go to File > Options >Customize Ribbon (1) and ensure the add-in is enabled under Main Tabs (2), see below four steps.

3. Check Disabled Items

Navigate to File > Options > Add-ins (1) and verify the add-in isn’t listed under Disabled Items (2). Enable it (3) if necessary.

4. ADd-ins Load behaviour I

In some Excel versions there is a bug with the load behavior; Then the add-in is not automatically loaded at the start of Excel; Go to File > Options > Add-ins (1), select Com Add ins (2), and ensure the add-in is listed and checked. (3).

If it’s not loaded (4), it might be a registry issue with the LoadBehavior setting. Ensure it’s set to 3 (automatic loading) in the registry under
HKEY_CURRENT_USER – Software – Microsoft -Office – Excel – Addins – NameOfYourAddin

See for more information : Microsoft Registry entries for VSTO Add-ins
Note: make sure you make a backup of the registry before making any changes.

4. ADd-ins Loadbehaviour II

If you receive, under Load Behavior (4), the message “Not loaded. A runtime error occurred during the loading of the COM Add-in,” this could be caused by several factors, including bitness mismatches (32-bit vs 64-bit). Ensure your Office installation and add-in bitness match. See for more information our Blog Difference 32-bit and 64-bit version of Excel.

For further troubleshooting, enable detailed VSTO error messages by following these steps:

• Open File Explorer and right-click on “PC.”
• Select Properties and choose Advanced system settings.
• Under System Variables, create a new variable named VSTO_SUPPRESSDISPLAYALERTS with a value of 0.

Then, relaunch Excel, and a more detailed error message should appear during the add-in loading process. This might help you resolve the “VSTO add-in not visible in Excel’s Ribbon” issue.