Throws an exception when opening an existing file

[Lydia-Shi]

Repro Steps

1. Create NET Core console application
2. Open Program.cs, add below code for Main method (\\winformtest\WinFormsRuntime\Libs\WFCTestLib\Util\Images\class.ico is an existing icon.)

            String fileName = @"\\winformtest\WinFormsRuntime\Libs\WFCTestLib\Util\Images\class.ico";
            // String fileName = @"C:\Users\v-qiashi\Desktop\Images\test.ico";

            Stream fs = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
            Icon ico = new Icon(fs);
            fs.Close();

3. Build and run

Actual result

Throw System.IO.IOException.

.NET Core Version

.NET 6.0.100-preview.7.21320.2

Regression?

Yes, this is a regression issue, it cannot repro on .Net 6.0.100-preview.6.21315.23.

More info

This issue not occurs when setting fileName to a local path, like:
String fileName = @"C:\Users\v-qiashi\Desktop\Images\test.ico";

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Issue Details

---

Repro Steps

1. Create NET Core console application
2. Open Program.cs, add below code for Main method (\winformssrvvm01\MDFile\WinFormsRuntime\Libs\WFCTestLib\Util\Images\class.ico is an existing icon.)

            String fileName = @"\\winformssrvvm01\MDFile\WinFormsRuntime\Libs\WFCTestLib\Util\Images\class.ico";
            // String fileName = @"C:\Users\v-qiashi\Desktop\Images\test.ico";

            Stream fs = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
            Icon ico = new Icon(fs);
            fs.Close();

3. Build and run

Actual result

Throw System.IO.IOException.

.NET Core Version

.NET 6.0.100-preview.7.21320.2

Regression?

Yes, this is a regression issue, it cannot repro on .Net 6.0.100-preview.6.21315.23.

More info

This issue not occurs when setting fileName to a local path, like:
String fileName = @"C:\Users\v-qiashi\Desktop\Images\test.ico";

Author:	Lydia-Shi
Assignees:	-
Labels:	area-System.IO, untriaged
Milestone:	-

[adamsitnik]

@Lydia-Shi big thanks for a very detailed bug report, I am going to fix it asap

[Lydia-Shi]

This issue has been fixed on .NET SDK latest build 6.0.100-preview.7.21324.6.