What is the possible cause for the below shown Exception

Question

1.00/5 (1 vote)

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.NET2.0

C#

{"
Current thread must be set to single thread apartment (STA) mode before OLE calls can be made. Ensure that your Main function has STAThreadAttribute marked on it.
"}

It happens when I initialize a runtime Combobox.

C#

this.cmbPlusPhysician.AutoCompleteMode = System.Windows.Forms.AutoCompleteMode.Suggest;

Posted 26-Aug-14 3:49am

KUMAR619

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[no name] 26-Aug-14 9:59am

Ensure that your Main function has STAThreadAttribute marked on it

KUMAR619 26-Aug-14 10:07am

Yes Sir, [STAThread] is above main function.
What may be the problem prevailing

Rob Philpott 26-Aug-14 10:23am

Are you using COM components? ActiveX?

You could try this (I doubt it will work but its worth a go, the apartment state will be set already)

Thread.CurrentThread.SetApartmentState(ApartmentState.STA);

[Edit] At the least, see what the value of the apartment state is on the GUI thread.

gggustafson 26-Aug-14 13:46pm

I have found there to be a difference between

public static void Main ( string [ ] args )

and

[ STAThread ]
public void Main ( string [ ] args )

I use the former.

Sergey Alexandrovich Kryukov 26-Aug-14 16:44pm

One cannot use non-static Main as entry point. The compiler will either say the entry point is not found, or some other function will be the entry point.

If [STAThread] is not added, STA will be assumed. OP maintains that [STAThread] is specified, but I doubt it (I remember this member for too long :-( ...).
The only other possibility would be that MTA is explicitly set in the thread running the code in question, as Ron Philpott shown (only the opposite, MTA), but I doubt it's the case...
I would rather believe that the problem is inadequately reported.

—SA

KUMAR619 27-Aug-14 1:52am

Sir It happen when particular control such as combobox initiates autocomplete mode.
Without using Autocomplete mode it works without error but when I use AutoComplete Mode
Error Occurs in the form of STA Thread Error

kbrandwijk 31-Aug-14 14:57pm

This problem has been mentioned a zillion times on this and other websites.

- Ensure on which thread you actually are when the error occurs. Are you doing something with BackgroundWorker, other Thread or anything?
- Ensure that the [STAThread] attribute is on your application entry point. Make sure that the method you think is actually your entry point (check project properties for startup object, look for overloads of the Main method)
- Make sure that the actual thread is in STA 'mode', by checking it using a breakpoint, and by setting ApartmentState on it if necessary

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What is the possible cause for the below shown Exception

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What is the possible cause for the below shown Exception

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