OutlookGoogleCalendarSync: Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG))

Out of interest, what screen capture program were you using there?

https://www.microsoft.com/en-us/p/screen-recorder-pro-for-win10/9n27gq6mls5s https://www.screentogif.com/

I know you ran regasm earlier on against the Microsoft.Office.Interop.Outlook.DLL shipped with OGCS, but essentially your problem is that Office should install and register the Primary Interop Assemblies (PIAs) automatically, but it doesn’t seem to have in your case.

Could you try searching for all instances of the Outlook PIA:

cd c:\
dir Microsoft.Office.Interop.Outlook.DLL /s

For me, outside of OGCS, I find them in:

• c:\Program Files\Microsoft Office\root\Office16\ADDINS\Microsoft Power Query for Excel Integrated\bin
• c:\Windows\assembly\GAC_MSIL\Microsoft.Office.Interop.Outlook\15.0.0.0__71e9bce111e9429c

I’d be interested if you have either of these - most importantly the 2nd one. If you do, please try registering:

cd c:\windows\Microsoft.NET\Framework64\v2.0.50727
regasm c:\Windows\assembly\GAC_MSIL\Microsoft.Office.Interop.Outlook\15.0.0.0__71e9bce111e9429c\Microsoft.Office.Interop.Outlook.DLL

new nst and ost, no pst involved

so I do tomorrow

1. restart / test
2. C:\Windows\Microsoft.NET\Framework64\v2.0.50727\regasm %LOCALAPPDATA%\OutlookGoogleCalendarSync\app-2.8.0-beta\Microsoft.Office.Interop.Outlook.DLL
3. restart / test
4. regsvr32 "inercomm.dll
5. restart / test