Form.ShowDialog in hidden application

Question

I have an application which runs in hidden mode. In new version I need to update database that is why I need to show some form to get some data from user for update. I use Form.ShowDialog method but errors occurred. It is said in error that

"Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application".

I guess that I need to show form in other way but I don't know how.

It works fine when i run this, i guess i should call it server, manually. But when another service starts it code:

  System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo(path);
  startInfo.WorkingDirectory = ServerModel.ServerInfo.ServerDir;
  startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
  System.Diagnostics.Process.Start(startInfo);

This error occurs.

Your code is calling or attempting to show a dialog from somewhere (middle tier, server, web service, windows service etc) where it cannot display that dialog or probably doesn't know what Windows Forms are for that matter. — skolte
– skolte, Commented Jan 31, 2014 at 8:09
If you cannot show a dialog, why would you be able to show any UI? — David Heffernan
– David Heffernan, Commented Jan 31, 2014 at 8:23
I mean startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden; — aleshko
– aleshko, Commented Jan 31, 2014 at 8:32

insomnium_ · Accepted Answer · 2014-01-31 08:11:56Z

2

I would suggest to use windows balloon notifications, as they are mean't for showing messages from hidden apps.

See this link for reference.

answered Jan 31, 2014 at 8:11

insomnium_

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2 Comments

David Heffernan Over a year ago

If ShowDialog() fails, so will balloon notifications

vgru Over a year ago

By "hidden" you mean "minimized to tray". OP's "hidden" app is running as a Windows Service app.

Patrick Hofman · Accepted Answer · 2014-01-31 08:19:50Z

1

As the error message says you have to set the options of MessageBox.Show to either ServiceNotification or DefaultDesktopOnly. This applies to a MessageBox you probably try to show in your application.

edited Jan 31, 2014 at 8:19

answered Jan 31, 2014 at 8:14

Patrick Hofman

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5 Comments

aleshko Over a year ago

I try to display not a messagebox but my defined winform.

Patrick Hofman Over a year ago

But I guess you are trying to show a MessageBox inside there. That is the error you get. But probably, as the other answer said, you want to rethink your application design.

Patrick Hofman Over a year ago

Any luck in find a solution?

aleshko Over a year ago

Actually i think the problem was in other thing. The special service start this server and that mean that windows don't know whom it should show ui.Actually when i delete startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden; line, even the descriptor of main window hadn't been create.That is why we remake the procedure of update.

Patrick Hofman Over a year ago

Okay, but it is possible to post messages or windows to the default desktop by using one of the options I described above. The service needs to have the Allow service to interact with desktop option checked.

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