net8.0-ios app crashes if minimised when a file is opened

[etigin]

Steps to Reproduce

1. Create new maui app
2. Include a file as Content or BundleResource
3. In MainPage class add the code that opens the file for reading
4. Deploy the app to an iPhone
5. Launch the app, minimise it and activate it again

Expected Behavior

App is resumed

Actual Behavior

App relaunches because it has crashed on minimising

[app<com.companyname.lockedfiletest(982B7E11-5EA0-4B25-9E4E-E809C83BFB63)>:1447] Terminating with context: <RBSTerminateContext| domain:15 code:0xDEAD10CC explanation:[app<com.companyname.lockedfiletest(982B7E11-5EA0-4B25-9E4E-E809C83BFB63)>:1447] was suspended with locked system files:
/var/containers/Bundle/Application/A3A31E01-7520-418A-8951-58AD7E2C90C8/LockedFileTest.app/data.bin
not in allowed directories:
/var/mobile/Containers/Data/Application/B0297286-77E2-4311-86F4-E6F82449A6D8
/var/mobile/Containers/Data/Application/B0297286-77E2-4311-86F4-E6F82449A6D8/tmp reportType:CrashLog maxTerminationResistance:Absolute>

The same code works correctly in Xamarin Forms. I've attached both examples.

Environment

Version information

JetBrains Rider 2023.3.2
Build #RD-233.13135.100, built on December 19, 2023

Runtime version: 17.0.9+7-b1087.9 aarch64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
macOS 14.2.1
.NET Core v7.0.10 ARM64 (Server GC)
GC: G1 Young Generation, G1 Old Generation
Memory: 4096M
Cores: 10
Metal Rendering is ON
Registry:
  editor.config.csharp.support=true
  ide.experimental.ui=true
Non-Bundled Plugins:
  com.jetbrains.rider.android (233.13135.100)
  com.intellij.ml.llm (233.13135.116)


$ dotnet --version                                                       
8.0.101

iPhone 12, iOS 17.2.1

LockedFileTest.zip
XamarinFormsExample.zip

[eugene-kruglik]

The same issue! Please give this high priority!

[rolfbjarne]

This is a behavioral difference between Mono and .NET: in .NET files are locked by default, while in Mono files weren't locked.

You can get the non-locking behavior in .NET by adding the following to your csproj:

<ItemGroup>
    <RuntimeHostConfigurationOption Include="System.IO.DisableFileLocking" Value="true" />
</ItemGroup>

[etigin]

Thanks a lot!

[rolfbjarne]

I've added a section about this to our document about breaking changes: https://github.com/xamarin/xamarin-macios/wiki/Breaking-changes-in-.NET#files-are-locked-by-default-in-net

[danieltharris]

This is a behavioral difference between Mono and .NET: in .NET files are locked by default, while in Mono files weren't locked.

You can get the non-locking behavior in .NET by adding the following to your csproj:

<ItemGroup>
    <RuntimeHostConfigurationOption Include="System.IO.DisableFileLocking" Value="true" />
</ItemGroup>

Is this approach still valid in .NET 9 MAUI apps?

[rolfbjarne]

This is a behavioral difference between Mono and .NET: in .NET files are locked by default, while in Mono files weren't locked.
You can get the non-locking behavior in .NET by adding the following to your csproj:

<ItemGroup>
    <RuntimeHostConfigurationOption Include="System.IO.DisableFileLocking" Value="true" />
</ItemGroup>

Is this approach still valid in .NET 9 MAUI apps?

Yes.