The requested clipboard operation failed

I've usin开发者_如何学编程g vb.net 2003 and some of the times this error arises. Can anyone know on how this error arises and how to fix it?

Error: The requested clipboard operation failed

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I googled this question to see what I'd see, and a lot of people have asked this question, and none of them have gotten a solid answer...

So I went to the MSDN documentation and found a note that explains what most people who have asked this question describe... The symptom usually appears when the user switches to another application while the code is running. The note is quoted below, with the link to the documentation following:

All Windows-based applications share the system Clipboard, so the contents are subject to change when you switch to another application.

An object must be serializable for it to be put on the Clipboard. If you pass a non-serializable object to a Clipboard method, the method will fail without throwing an exception. See System.Runtime.Serialization for more information on serialization. If your target application requires a very specific data format, the headers added to the data in the serialization process may prevent the application from recognizing your data. To preserve your data format, add your data as a Byte array to a MemoryStream and pass the MemoryStream to the SetData method.

The Clipboard class can only be used in threads set to single thread apartment (STA) mode. To use this class, ensure that your Main method is marked with the STAThreadAttribute attribute.

Special considerations may be necessary when using the metafile format with the Clipboard. Due to a limitation in the current implementation of the DataObject class, the metafile format used by the .NET Framework may not be recognized by applications that use an older metafile format. In this case, you must interoperate with the Win32 Clipboard application programming interfaces (APIs). For more information, see article 323530, "Metafiles on Clipboard Are Not Visible to All Applications," in the Microsoft Knowledge Base at http://support.microsoft.com.

http://msdn.microsoft.com/en-us/library/system.windows.forms.clipboard.aspx

Funnily enough, this makes sense of a strange behavior I noticed in one of my own apps. I have an app that writes to an Excel spreadsheet (actually, to hundreds of them, modifying hundreds of cells each). I don't use the clipboard at all, just the Interop API for excel, yet when it's running, my clipboard clears every time a new spreadsheet is created. In my case, Excel is messing with the clipboard, even there is no discernible reason for it to do so. I'd chalk it up to one of those mysterious Windows phenomena that we mortals will never understand.

At any rate, thanks to your question, I think I understand my issue, so +1 to you for helping me out.

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I have that error while trying to:

Clipboard.Clear();
...
Clipboard.SetText(...);

For solving it I replace Clipboard.Clear() with pinvoking some methods from the user32.dll:

[DllImport("user32.dll")]
static extern IntPtr GetOpenClipboardWindow();

[DllImport("user32.dll")]
private static extern bool OpenClipboard(IntPtr hWndNewOwner);

[DllImport("user32.dll")]
static extern bool EmptyClipboard();

[DllImport("user32.dll", SetLastError=true)]
static extern bool CloseClipboard();

...

IntPtr handleWnd = GetOpenClipboardWindow();
OpenClipboard(handleWnd);
EmptyClipboard();
CloseClipboard();

...

Clipboard.SetText(...);

I use C# here, but vb version could be easily created from it.

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Is there a chance that UltraVNC is running. I have issues when that application is running in the background on the client PC side. When I close VNC, I can copy to the clipboard successfully. This is not really a satisfying solution but at least I know in my case the source of the problem.