Unable to cast COM object of type 'System.__ComObject' to interface type 'Interop.QBXMLRP2.RequestProcessor2'

Install the QuickBooks SDK OUT OF SCOPE OF SUPPORT

Problem

You cannot run your web connector successfully.

Description

Please use the following at your own risk, If this does not fix the problem it has been noted that completely reinstalling QuickBooks has worked for some users. (make sure to backup your company file before this process) This is out of our scope of support we are not liable for any problems occurring from doing this it is recommended to contact Intuit. 

Your Connex log shows this error:

WebMethod: connectionError() has been called by QBWebconnector13101310Parameters received:1310string ticket = 81640146-335f-4aad-bb0b-26c168c525901310string hresult = Exception 1310string message = Unable to cast COM object of type 'System.__ComObject' to interface type 'Interop.QBXMLRP2.RequestProcessor2'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{8DB91B17-D5A2-41DB-80A7-CC6F1E449A05}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).13101310HRESULT = Exception 1310Message = Unable to cast COM object of type 'System.__ComObject' to interface type 'Interop.QBXMLRP2.RequestProcessor2'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{8DB91B17-D5A2-41DB-80A7-CC6F1E449A05}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).1310Sending empty company file to try again.1310Return values: 1310string retVal = 1310    

Solution

Install the QuickBooks SDK

You must run the QBXMLRP2Installer.exe. Please go here:  in C:\Program Files (x86)\Intuit\IDN\QBSDK13.0\tools\installers

If you are missing the QuickBooks SDK, go here:

https://developer.intuit.com/app/developer/qbdesktop/docs/get-started/download-and-install-the-sdk

Install the SDK and reboot your machine.