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Load Excel add-in using win32com from Python

Posted by: admin March 9, 2020 Leave a comment


I’ve seen from various questions on here that if an instance of Excel is opened from Python using:

xl = win32com.client.gencache.EnsureDispatch('Excel.Application')
xl.Visible = True
wb = xl.Workbooks.Open('Test.xlsx')

Then it does not load the default add-ins. I’ve tried forcing my add-in to load by instead running:

xl = win32com.client.gencache.EnsureDispatch('Excel.Application')
xl.Visible = True
addin = xl.Workbooks.Open('C:/path/addIn.xll')
wb = xl.Workbooks.Open('Test.xlsx')

However, when I do this an instance of Excel opens and I get a security message asking me to verify I want to open this add-in. If I click “Enable this add-in for this session only” Excel immediately closes and does not open my desired xlsx file.

Does anyone have any ideas how to force the add-in to load and then to allow me to open my file?

Thanks very much for your help!

How to&Answers:

I have actually managed to resolve this by borrowing something from this MSDN article relating to doing the same thing with VBA:


The following now works perfectly:

xl = win32com.client.gencache.EnsureDispatch('Excel.Application')
xl.Visible = True
wb = xl.Workbooks.Open('Test.xlsx')


I had the same problem, but couldn’t use xl.RegisterXLL('C:/path/addin.xla') from the accepted answer, because it only works with .XLL files, and I had a .XLA file.

Instead, I found that this worked:

xl = win32com.client.gencache.EnsureDispatch('Excel.Application')

# Need to load the addins before opening the workbook
addin_path = r'C:\path\addin.xla'
xl.AddIns.Add(addin_path).Installed = True

wb = xl.Workbooks.Open(r"C:\my_workbook.xlsm")


I have had much better success using Excel via win32com than any of the other methods, but you might want to look at pyxll (https://www.pyxll.com/introduction.html). Here are a few other things:

  • Have you checked that addin.Installed == True?
  • Have you tried AddIns.Add("c:\windows\addins\TSXL\TSXL.xll").Installed = True?
  • Try xl.DisplayAlerts=False before opening the workbooks
  • Have you tried the four steps in last answer of Automating Excel via COM/Python – standard addins won’t load at startup, I copy them here:

    1. Open the XLA / XLL file representing the addin in question
    2. Set addins(addin_name).Installed = False
    3. Addins(addin_name).Add(addin_file_path)
    4. Set addins(addin_name).Installed = True