Why can't catch FileOpenPicker->PickSingleFileAsync unhandled exception?

Question

Hi all,

I can't catch the exception when cancel theFileOpenPicker->PickSingleFileAsync operation.

FileOpenPicker^ picker = ref new FileOpenPicker();	
picker->FileTypeFilter->Append(".mp4");
picker->SuggestedStartLocation = PickerLocationId::VideosLibrary;

task<StorageFile^> m_pickFileTask(picker->PickSingleFileAsync());
m_pickFileTask.then([this](StorageFile^ files)
{
	try
	{
		x_tb1->Text = "bn3 click" + files->DisplayName->ToString();	
	}
	catch(Platform::Exception^ e)
	{
		x_tb1->Text = "bn3 exception";	
	}
	catch(...)
	{
		x_tb1->Text = "bn3 all exception";	
	}
});

In general,
The x_tb1->Text will same as the file name when I selected by FileOpenPicker

But,
When I doesn't select anyone, and cancel the operation.
The parameter "files" should be null pointer.
So, I want using try-catch to avoid this situation.

The actual result is show a unhandled exception dialog.
It means the try-catch doesn't catch this exception.
Why?
Is there any mistake for my code?

Thanks

Answer 1

I'd do a nullptr check instead of relying on exception handling for this case.

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Answer 2

Hello,

You can try these code to catch the error when you get the StorageFile from  PickSingleFileAsync()

task<StorageFile^> m_pickFileTask(picker->PickSingleFileAsync());
m_pickFileTask.then([this](task<void> t)
{
	try
	{
	       StorageFile^ files=safe_case<StorageFile^>(t.get());
	}
	catch(Platform::Exception^ e)
	{
		x_tb1->Text = "bn3 exception";	
	}
	catch(...)
	{
		x_tb1->Text = "bn3 all exception";	
	}
});

Best regards,

Jesse

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Jesse Jiang [MSFT]
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