Clean .NET MAUI iOS app crashes on launch when `_ExportSymbolsExplicitly=false`

[sztechmiler]

Apple platform

iOS

Framework version

net10.0-*

Affected platform version

Known failing: - .NET SDK: 10.0.101 - Workload set: 10.0.203.1 - iOS workload: 26.4.10259 - Xcode: 26.4.1 - Device build: physical iPhone Also failing: - Workload set: 10.0.303.3 - Xcode: 26.5 - Device build: physical iPhone Known working: - Workload set: 10.0.300 - iOS workload: 26.2.10233 - Xcode: 26.3 - _ExportSymbolsExplicitly=false

Description

A clean .NET MAUI iOS application created from dotnet new maui crashes immediately on launch on a physical iPhone when this property is set:

<PropertyGroup Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">
  <_ExportSymbolsExplicitly>false</_ExportSymbolsExplicitly>
</PropertyGroup>

The same clean app launches successfully when the property is removed or set to true.

This appears to be a regression in the .NET for iOS/macios toolchain. It is not caused by app code or third-party packages: the repro project only references the default MAUI packages.

Steps to Reproduce

Create a new MAUI app:

dotnet new maui -n ExportFalseMauiIos -o ExportFalseMauiIos

Use an iOS-only project with this property:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFrameworks>net10.0-ios</TargetFrameworks>
    <OutputType>Exe</OutputType>
    <RootNamespace>ExportFalseMauiIos</RootNamespace>
    <UseMaui>true</UseMaui>
    <SingleProject>true</SingleProject>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <ApplicationTitle>Export False MAUI iOS</ApplicationTitle>
    <ApplicationId>pl.benefitsystems.multisport.dev.local</ApplicationId>
    <ApplicationDisplayVersion>1.0</ApplicationDisplayVersion>
    <ApplicationVersion>1</ApplicationVersion>
    <RuntimeIdentifier Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">ios-arm64</RuntimeIdentifier>
    <SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">17.0</SupportedOSPlatformVersion>
  </PropertyGroup>

  <PropertyGroup Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">
    <_ExportSymbolsExplicitly>false</_ExportSymbolsExplicitly>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Maui.Controls" />
    <PackageReference Include="Microsoft.Extensions.Logging.Debug" />
  </ItemGroup>
</Project>

Publish and install to a physical iPhone:

dotnet publish ExportFalseMauiIos/ExportFalseMauiIos.csproj \
  --configuration Release \
  --self-contained \
  --framework net10.0-ios \
  -r ios-arm64 \
  -p:ArchiveOnBuild=true \
  -p:CodesignKey="Apple Development: ..." \
  -p:CodesignProvision="..."

Install the generated IPA and launch the app.

Expected Behavior

The app should launch and show the initial MAUI page.

Actual Behavior

The app crashes immediately on launch before the first page is usable.

Changing only this:

<_ExportSymbolsExplicitly>false</_ExportSymbolsExplicitly>

to either removing the property or:

<_ExportSymbolsExplicitly>true</_ExportSymbolsExplicitly>

makes the same clean app launch successfully.

Test Matrix

Xcode	Workload set	iOS workload	_ExportSymbolsExplicitly	Result
26.3	10.0.300	26.2.10233	false	works
26.4.1	10.0.203.1	26.4.10259	false	crashes on launch
26.4.1	10.0.203.1	26.4.10259	true/default	works
26.5	10.0.303.3	26.5.10284	false	crashes on launch

Did you find any workaround?

Remove the property or set it to true:

<_ExportSymbolsExplicitly>true</_ExportSymbolsExplicitly>

However, this property was previously used as a workaround for Firebase Crashlytics symbol/crash reporting behavior, so removing it may affect crash reporting. Crashlitics bug workaround

Another workaround is to pin to the older working stack:

• Xcode 26.3
• Workload set 10.0.300
• iOS workload 26.2.10233

Possibly Related Issues / PRs

I did not find an exact existing open issue for this launch crash.

Related symbol export / strip PR:

• [msbuild] Don't pass symbol file to strip when _ExportSymbolsExplicitly=false. Fixes #24582. #24800

This issue may be related to the change in #24800, but the symptom is different:

• Strip exited with code 1 can't open mtouch-symbols.list when setting _ExportSymbolsExplicitly=false #24582 / [msbuild] Don't pass symbol file to strip when _ExportSymbolsExplicitly=false. Fixes #24582. #24800: build-time strip failure around mtouch-symbols.list
• this issue: build succeeds, install succeeds, app crashes at runtime on launch

Relevant logs

No response

[rolfbjarne]

@sztechmiler do you need this for Craslytics/Firebase? If so, can you see if adding this to your csproj works as a different workaround?

<ItemGroup>
    <ReferenceNativeSymbol Include="_mh_execute_header" SymbolType="Function" />
</ItemGroup>

From: #25427 (comment)

[sztechmiler]

@rolfbjarne -> adding _mh_execute_header seems to fix the crashlitics issue so I no longer need _ExportSymbolsExplicitly == false.
Thanks for quick response and workaround!