System.NullReferenceException : Arg_NullReferenceException
at System.IO.FileStream.ReadAsync(Memory`1 buffer, CancellationToken cancellationToken)
at System.IO.StreamReader.ReadBufferAsync(CancellationToken cancellationToken)
at System.IO.StreamReader.ReadToEndAsyncInternal(CancellationToken cancellationToken)
at Microsoft.Maui.Essentials.DeviceTests.FileSystem_Tests.CheckFileResultOpenReadAsyncMultipleTimes()
--- End of stack trace from previous location ---
{
"ErrorMessage": [
"at System.IO.FileStream.ReadAsync",
"at Microsoft.Maui.Essentials.DeviceTests.FileSystem_Tests."
],
"BuildRetry": false,
"ExcludeConsoleLog": false
}
Build Information
Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1497568
Leg Name: maui-pr-devicetests / net11.0 CoreCLR iOS Helix Tests (Run DeviceTests iOS) and net11.0 CoreCLR MacCatalyst Helix Tests (Run DeviceTests MacCatalyst)
Error Details
Microsoft.Maui.Essentials.DeviceTests.FileSystem_Testsfail on the net11 CoreCLR iOS and MacCatalyst device-test legs with aNullReferenceExceptionthrown fromSystem.IO.FileStream.ReadAsync. Affected tests includeCheckFileResultOpenReadAsyncMultipleTimesand everyOpenAppPackageFileAsync_Can_Load_Filecase (5 failures per leg). The non-zero XHarness exit also surfaces as a work-item levelWorkItemExecutionfailure for the same Essentials work item.Error Message
{ "ErrorMessage": [ "at System.IO.FileStream.ReadAsync", "at Microsoft.Maui.Essentials.DeviceTests.FileSystem_Tests." ], "BuildRetry": false, "ExcludeConsoleLog": false }Known issue validation
Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1497568
Error message validated:
[at System.IO.FileStream.ReadAsync at Microsoft.Maui.Essentials.DeviceTests.FileSystem_Tests.]Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 7/7/2026 8:47:43 PM UTC
Report
Summary