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2145890 - Error "Unable to cast COM object of type" in Outlook Add-in


You installed the first time the SAP Outlook Add-in after launching Microsoft Outlook, you have the following error:

Unable to cast COM object of type 'Microsoft.Office.Interop.Outlook.ApplicationClass' to interface type 'Microsoft.Office.Interop.Outlook._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{00063001-0000-0000-C000-000000000046}' failed due to the following error: Library not registered.

Reproducing the Issue

  1. Install SAP Outlook Add-in
  2. Open Microsoft Office
  3. Error


The issue is caused by a wrong registry file, this happens when you downgrade the version of Microsoft Office .e.g. 2010 to 2007.

Registry Key: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046}

Here you will see that you have for example folders with numbers: 9.3, 9.4 or 9.5 - it depends of the versions of the Microsoft Packages

Outlook 2007      9.3

Outlook 2010      9.4

Outlook 2013      9.5

So when you downgrade, these folders are not deleted, if you went from Office 2010 the 9.4 will be present together with 9.3 from Office 2007.


You should delete the folder related to the Microsoft Office that IS NOT installed in the computer.


If you have the 9.4 folder (from Office 2010) and you are using Office 2007 (folder 9.3). You should delete the folder 9.4, related to the Office 2010 that you do not have installed in your computer, inside the registry key:



Obsevation: All of that with any program from Microsoft Office Package open (Excel/Outlook etc.)


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