Load an Excel Add-In

Accepted answer

If it's an .xla file rather than a COM add-in, then you should be able to open it from the Workbooks collection.

The code will be something like this:

Excel.Workbook addIn = oXL.Workbooks.Open(pathToXLAFile); // assuming .NET 4.0

addIn.RunAutoMacros(XlRunAutoMacro.xlAutoOpen); // if needed

Maybe the key is I was missing the addIn qualifier! I was trying the same code (minus the addIn) and it would just freeze up my Excel and force me to CTRL+ALT+DEL to get out of everything.

richard smith13y ago

I saw that post, my only difference is that I am dealing with a .xla file and they are using a .XLL file, which are two different filetypes. :(

Vulpes13y ago

I found a thread about it here:

http://stackoverflow.com/questions/1154558/how-to-load-an-excel-addin-using-interop

As you can see, there seems to be a problem if the add-in is already installed - you have to uninstall it, reinstall it and then load it. However, the OP may have found a possible solution to this as long as a workbook is already open.