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When trying to push an email via the Advanced push, you may run into the following exception:

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. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)).

The root cause is that the version reference for the TypeLib created by the Outlook installation is pointing to an incorrect value.

This issue can occur, amongst other things, when downgrading Microsoft Office installation or when different versions of different Microsoft Office programs are running on the same computer.

You can resolve this issue by following the instructions below (you need to have Administrator privileges on your machine to do so):

Using Registry Editor incorrectly can cause serious system-wide issues that may require you to re-install Windows to fix them.
So, before making any changes in the Windows Registry, we strongly recommend that you make a backup of the registry first and contact your internal IT staff for assistance to perform these changes.
For more information about how to back up and restore the registry in Windows, please refer to this Microsoft article.
  1. Close Outlook.
  2. Uninstall the Outlook Add-in.
  3. Check the Interface:
    • Press the Windows key on your keyboard simultaneously with the R key to bring up the "Run" box then type in Regedit and press Enter.
    • In the Windows Registry Editor, navigate to HKEY_CLASSES_ROOT\WOW6432Node\Interface\{00063001-0000-0000-C000-000000000046}\TypeLib.
      If your computer is running a 32-bit version of Windows, you will find the registry key for the interface in a different location: HKEY_CLASSES_ROOT\Interface\{00063001-0000-0000-C000-000000000046}\TypeLib.
    • Then find a "(Default)" entry with the value "{00062FFF-0000-0000-C000-000000000046}"
    • You should find a "Version" entry. Check that this version matches the value in the following table based on the version of Outlook currently installed on your computer.
      Microsoft Outlook Version Registry Version entry
      Outlook 2019 9.7
      Outlook 2016 9.6
      Outlook 2013 9.5
      Outlook 2010 9.4


  1. Fix the TypeLib
    • In the Windows Registry Editor, navigate to HKEY_CLASSES_ROOT\Wow6432Node\TypeLib\{00062FFF-0000-0000-C000-000000000046}.
      If your computer is running a 32-bit version of Windows, you will find the registry key for the interface in a different location: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046}.
    • Delete the version keys for any version of Outlook that is not installed on your system (please refer to the version table provided above).
      For example, if you are not using Outlook 2013 then remove the "9.5" entry.
      Do not delete the entry for the version that was configured in Step 3.
    • In short, you will only keep the version key corresponding to the Outlook version that is currently installed on your computer.
  2. Run a repair on your Microsoft Office installation
  3. Restart your computer
  4. Reinstall the Outlook Add-in
  5. Start Outlook
  6. Check that you can now use the Outlook Add-in properly