Crystal Reports - Value cannot be null. Parameter name: window

Question

I recently came across an unusual error when attempting to load a crystal report form into my WPF application via a dialog, the report would show as loading for a few seconds and then throw an error stating "Value cannot be null. Parameter name: window" This confused me, as far as i know, crystal reports doesn't use a parameter named window. This was my code: A simple window with a `CrystalReportsViewer` ``` ``` and loading the report from code behind (I've removed the standard ConnectionInfo code for simplicity) ``` cryRpt = new ReportDocument(); cr…

Accepted Answer

Turns out that Crystal Reports Does indeed use a parameter named window, when it attempts to show an internal error.

`CrystalReportsViewer` handles internal an error and will try to show a MessageBox:

`System.Windows.MessageBox.Show(Window owner, String messageBoxText, String caption, MessageBoxButton button, MessageBoxImage icon)`

Show method get u201CWindow owneru201D parameter and CrystalReportsViewer tries pass Owner property CrystalReportsViewer.Owner, however by default owner is null, as such we get this unexpected error.

A simple fix for this, is in the codebehind (even when using mvvm) we simply set the owner to the current window via the following code:

```
ReportView.Owner = Window.GetWindow(this);
```

Do this in the OnLoaded Event or similar, and you will find that now you get a messagebox with an internal error thrown by `CrystalReportsViewer`.

Credit for this solution belongs to this thread

Crystal Reports - Value cannot be null. Parameter name: window

Solution

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