Author: William Gerbert

OLE Error: CoInitialize has not been called

Answer:

In a project that needed to display HTML documents, I decided to use the 
TWebBrowser control. I had used this handy ActiveX control successfully in other 
projects before.

This application was an MDI application, written in Delphi 5. As a 'specialty' I 
had installed a beta version of Internet Explorer on my system. I am not sure which 
of this is responsible for it, but when I would call the function in my application 
to display the HTML document, the TWebBrowser element could not be instantiated.
Instead I would receive an error message:

'CoInitialize has not been called'

The surprising thing is that the webbrowser control shows fine in design mode! I 
checked and TWebBrowser was properly installed. The underlieing DLL was also 
registered properly. A call of

regsvr32 shdocvw.dll

did not help. Finally I manually called the CoInitialize() function. I had to add 
OLE2 to the list of used units. A good place to do this is the initialization part 
as the sample snippet below shows.


1   uses
2     OLE2, // <-- make sure to include this unit
3     Windows; // and others
4   
5   initialization
6     CoInitialize(nil); // <-- manually call CoInitialize()
7   
8   end.