Interpreting Error Codes

After you have determined which application is the source of a problem, you need to find out what error has occurred. Errors are raised and reported in different formats, depending on the language your application uses.

In Microsoft Visual C++, success, warning, and failure values are returned using a 32-bit number known as a HRESULT. For a list of system-defined HRESULT values, see the header file Winerror.h included with the Windows SDK. This file includes all COM+ error codes and descriptions. For more information about HRESULT values, see Error Handling.

In the Java language, an instance of com.ms.com.ComFailException is thrown to indicate failure, where the ComFailException object specifies an HRESULT. An instance of com.ms.com.ComSuccessException indicates success with a return value of False. For information about interpreting these exceptions, see the Microsoft Visual J++ documentation.

Note

COM+ application server processes that are hosting Visual J++ objects will not idle down (even with zero active objects) unless you turn off JIT debugging in the VJ6 IDE. For information on how to do so, see the Visual J++ documentation.

In Visual Basic, you can retrieve HRESULT values by examining the Err.Number property. A description of the error can be retrieved with the Err.Description property.

You can also use the ERRLOOK utility in Microsoft Visual Studio to retrieve a system error message or module error message. ERRLOOK retrieves the error message text automatically if you drag-and-drop a hexadecimal or decimal value from the Visual Studio debugger or other Automation-enabled application. You can also enter a value by either typing it in or pasting it from the IDE clipboard and clicking the Look Up option.

The following C++ method prints a description of the error, based upon the input HRESULT.

#include <stdio.h>
#include <windows.h>
#include <tchar.h>

void ErrorDescription(HRESULT hr) 
{ 
     if(FACILITY_WINDOWS == HRESULT_FACILITY(hr)) 
         hr = HRESULT_CODE(hr); 
     TCHAR* szErrMsg; 

     if(FormatMessage( 
       FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM, 
       NULL, hr, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), 
       (LPTSTR)&szErrMsg, 0, NULL) != 0) 
     { 
         _tprintf(TEXT("%s"), szErrMsg); 
         LocalFree(szErrMsg); 
     } else 
         _tprintf( TEXT("[Could not find a description for error # %#x.]\n"), hr); 
}

The following table provides descriptions of common error codes in COM+.