SAP:Unable to cast COM object of type ‘System.__ComObject’ to interface type ‘SAPbobsCOM.ICompany’

SAP Business One DI API

I kept getting the above error when attempting to generate documents on a thread other than the main thread. Here’s the error message in full:

Unable to cast COM object of type ‘System.__ComObject’ to interface type ‘SAPbobsCOM.ICompany’. This operation failed because the QueryInterface call on the COM component for the interface with IID ‘{3BA8DAED-5B33-4CE4-A4B8-B4308D86E524}’ failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).
 

Turns out that running the following command on the client machine did the trick:

C:\SAP\SAP Business One DI API\DI API 88>regsvr32 SAPbobsCOM88.dll

What was weird here was that previous calls to the COM object on the main thread work fine. Any subsequent calls on a different thread threw the exception.

Incidentally, I have also spotted this error when using some 3rd party (and SAP – Certified) add-ons. In all cases, the above DLL registration command resolved the issue. Your mileage may vary, however.

For more information on the SAP Business One DI API, check out the following link over at the SBO website:

http://scn.sap.com/docs/DOC-7722