exception on binding WPF BitmapImage and german umlauts are used in file names (dotnet 9.0.0 / windows 11)

[wd72]

Description

when using filenames on an UNC network share with german umlauts (ü,ö,ä) an Exception is thrown.

Reproduction Steps

use 2 files on unc network path:

\\ps-nas\Temp\products\TestU\testImage.jpg
\\ps-nas\Temp\products\TestÜ\testImage.jpg

WPF Code: (Windows Platform)

<Image Stretch="Uniform" StretchDirection="DownOnly" HorizontalAlignment="Center" Width="300" Height="300">
    <Image.Source >
       <BitmapImage UriSource="{Binding FullFileName2}" CacheOption="OnLoad" />
    </Image.Source>
</Image>

ViewModel/Model Code:

    public string FullFileName2 { get { return @"\\ps-nas\Temp\products\TestU\testImage.jpg"; } }   // --> this works
    public string FullFileName2 { get { return @"\\ps-nas\Temp\products\TestÜ\testImage.jpg"; } }   // --> this does not work 

Expected behavior

german umlauts in filenames should work like in dotnet 8.

Actual behavior

Inner Exception 1:
DirectoryNotFoundException: Could not find a part of the path '\\ps-nas\temp\products\testü\testimage.jpg\Temp\products\TestÜ\testImage.jpg'.

the Image class does not use the provided path an appends something weird. --> the modified file name does not exist --> Exception.

wrong filename:
\\ps-nas\temp\products\testü\testimage.jpg\Temp\products\TestÜ\testImage.jpg
should be:
\\ps-nas\temp\products\testü\testimage.jpg

Regression?

this bug does not occur in dotnet 8

Known Workarounds

No response

Configuration

dotnet 9.0.0, Windows 11 24H2,

   <TargetFramework>net9.0-windows</TargetFramework>
   <Nullable>enable</Nullable>
   <UseWPF>true</UseWPF>
   <UseWindowsForms>true</UseWindowsForms>
   <PlatformTarget>x64</PlatformTarget>

Other information

No response

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[adamsitnik]

the Image class does not use the provided path an appends something weird

Because of that I've moved the issue to WPF.

[miloush]

@adamsitnik I am afraid that was a bit premature. Here is a repro not involving WPF:

Uri bse = new Uri("http://microsoft.com");
Uri rel = new Uri(@"\\ps-nas\Temp\products\TestÜ\testImage.jpg");
Uri u = new Uri(bse, rel); // {file://ps-nas\temp\products\testü\testimage.jpg/Temp/products/TestÜ/testImage.jpg}

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[adamsitnik]

@miloush big thanks for catching that!

I've moved it back to dotnet/runtime and added to System.Net area.

The repro:

Uri bse = new Uri("http://microsoft.com");
Uri rel = new Uri(@"\\ps-nas\Temp\products\TestÜ\testImage.jpg");
Uri u = new Uri(bse, rel); // {file://ps-nas\temp\products\testü\testimage.jpg/Temp/products/TestÜ/testImage.jpg}
Console.WriteLine(u.ToString());

> dotnet run -c Release -f net8.0
file://ps-nas/Temp/products/TestÜ/testImage.jpg
> dotnet run -c Release -f net9.0
file://ps-nas\temp\products\testü\testimage.jpg/Temp/products/TestÜ/testImage.jpg