PRB: Error 0x80020004 (-2147352572) When Setting a Property

• Microsoft Win32 Software Development Kit (SDK)

SYMPTOMS

You get the error DISP_E_PARAMNOTFOUND when you try to set a property.

CAUSE

The DISPPARAMS structure must be initialized in a special way for DISPATCH_PROPERTYPUT or DISPATCH_PROPERTYPUTREF.

RESOLUTION

When you use IDispatch::Invoke() with DISPATCH_PROPERTYPUT or DISPATCH_PROPERTYPUTREF, you have to specially initialize the cNamedArgs and rgdispidNamedArgs elements of your DISPPARAMS structure with the following:

   DISPID dispidNamed = DISPID_PROPERTYPUT;
   dispparams.cNamedArgs = 1;
   dispparams.rgdispidNamedArgs = &dispidNamed;

STATUS

This behavior is by design.

MORE INFORMATION

This behavior is necessary because some OLE Automation servers, as a result of their language structure, cannot differentiate between a property get or put and a method call. This specially named argument case is used to determine what is actually going on.

REFERENCES

"Inside OLE," Kraig Brocksmidt, Chapter 14, "The IDispatch interface" section, Microsoft Press, 1995