What is this error in Outlook plugin log?

Question

Test pass however sidepanel shows otherwise~ Log error below: 2018-12-05 17:00:00,481 [VSTA_Main] ERROR Sugar.Outlook.Outlook - RDOSession can't be initialized System.InvalidCastException: 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: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)). at System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc, IntPtr pCPCMD, IntPtr& ppTarget, Boolean& pfNeedsRelease) at Microsoft.Office.Interop.Outlook.ApplicationClass.get_Session() at Sugar.Outlook.Outlook.OpenRDOSession() Does anybody knows how to solve this error?

Yan Yu Yong · Accepted Answer

This can be caused by wrong registry keys left from previous installed versions of Microsoft Office. Usually this is a case when Office was downgraded. In order to fix this problem you need to remove these wrong registry keys. Close all instances of Microsoft Outlook. Open the Windows Registry Editor (run regedit.exe). Navigate to the following registry path: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046} . Check what keys you have in this path. Each version of Outlook has its key: For O utlook 2010 the key is 9.4 . For O utlook 2013 the key is 9.5 . For Outlook 2016 the key is 9.6 . You need to keep only one key that corresponds to installed Outlook version. All other keys have to be removed. Restart your system for the changes to take effect.