title: Excel Custom Functions using Add-Ins: "This add-in is no longer available" error
body: <p>I followed all of the steps <a href="https://docs.microsoft.com/en-us/office/dev/add-ins/quickstarts/excel-custom-functions-quickstart?tabs=excel-windows" rel="nofollow noreferrer">here</a> to try and load in a basic excel custom function add in. Everything in the setup stages seems to work, however, when I run 'npm run start:desktop' and Excel opens, there is an error on the side that says: </p>
  
  <blockquote>
    <p>ADD-IN ERROR This add-in is no longer available: add-ins inserted during development are only available during debugging from Visual Studio. Please open your project in Visual Studio and re-run your application, or deploy your application into a valid catalog and re-insert</p>
  </blockquote>
  
  <p>I get this error whether I run the project from the command line, VS Code, or Visual Studio. I am on Windows 10 using Excel 2016. </p>
  
  <p>Here is a photo of the Excel page with the error: <a href="https://i.stack.imgur.com/ehQ1R.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ehQ1R.png" alt="enter image description here"></a></p>