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OLE Error: CoInitialize has not been called
50 comments. Current rating: 
(34 votes). Leave comments and/ or rate it.
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.
Thanks to Martin Vreeken for pointing out the necessary CoUninitialize() call.
Note:
In a multithreaded application, you have to put a call to CoInitialize() at the beginning of your thread's Execute method and a matching CoUnInitialize() at its end.
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uses ActiveX, // <-- make sure to include this unit // older Delphi versions use: OLE2 instead Windows; // and others initialization CoInitialize(nil); // <-- manually call CoInitialize() finalization CoUnInitialize; // <-- free memory end. | ||
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Comments:
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Good point!
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Perfect
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Super
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Thanks for advertizing this problem and its solution. I was about to quit an undebugged program (a DLL actualy, involving a TwebBrowser), and planning to forget about it when I thought to have a look on the web ... and found what the problem was.
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Super duper.. It fixed the current problem leading me onto the next DLL-related /%#/!'%#/!' error.
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Thanks you so much ! That resolved my bug ! Thanks again ! You re so Pro :D
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Thank you! This also resolved a problem of a TADOConnection throwing random exceptions when created programmatically in a DLL (Delphi 7).
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i had the same problem with MS Word automation....
I'll try your hint. thanks a lot | ||
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Life saver, thanks a million.
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Valeu
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Unfrotunately it didn't solve the problem of TSimpleRSS and TIdHTTP being called from a separate thread. I don't know WTF is happending. :( I added CoInitialize all over the place, and the error still appears.
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I used this in my new procedure:
procedure CreateShortcut(const ShortCutName: string; OnDesktop: boolean); It worked perfectly in the pasts without initializing with CoInitialize but suddenly is dropped that error message so I used your solution: procedure CreateShortcut(const ShortCutName: string; OnDesktop: boolean); { OnDesktop: 1=Desktop 0=StartMenu } var MyObject : IUnknown; MySLink : IShellLink; MyPFile : IPersistFile; Directory : String; WFileName : WideString; MyReg : TRegIniFile; begin CoInitialize(nil); <----- //OLD CODE ... MyObject := CreateComObject(CLSID_ShellLink); MySLink := MyObject as IShellLink; MyPFile := MyObject as IPersistFile; //OLD CODE ... CoUninitialize; <----- end; Gabriel newfedra at yahoo.com | ||
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I also would like to thank for this tip -> it allowed me to save a lot of time which I would otherwise spend on fighting with thread-createad ADOConnection :)
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Worked great for me when trying to auotmate Excel.
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Great help!
That fixed the winshell.pas unit I found elsewhere, enabling me to read the content of a desktop shortcut. Thank you so much! Manfred | ||
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