Document .NET 11 Assembly.GetCallingAssembly behavior with StackTraceSupport=false

docs/core/compatibility/11.md

@@ -22,6 +22,7 @@ See [Breaking changes in ASP.NET Core 11](/aspnet/core/breaking-changes/11/overv
 
 | Title                                                             | Type of change    |
 |-------------------------------------------------------------------|-------------------|
+| [Assembly.GetCallingAssembly behavior changes when stack trace support is disabled](core-libraries/11/assembly-getcallingassembly-stacktracesupport-disabled.md) | Behavioral change |
 | [CborReader and CborWriter enforce a default maximum nesting depth](core-libraries/11/cbor-max-depth.md) | Behavioral change |
 | [CRC32 validation added when reading ZIP archive entries](core-libraries/11/ziparchive-entry-crc32-validation.md) | Behavioral change |
 | [DateOnly and TimeOnly TryParse methods throw for invalid input](core-libraries/11/dateonly-timeonly-tryparse-argumentexception.md) | Behavioral change |

docs/core/compatibility/core-libraries/11/assembly-getcallingassembly-stacktracesupport-disabled.md

@@ -0,0 +1,46 @@
+---
+title: "Breaking change: Assembly.GetCallingAssembly behavior changes when stack trace support is disabled"
+description: "Learn about the breaking change in .NET 11 where Assembly.GetCallingAssembly can throw NotSupportedException when stack trace support is disabled."
+ms.date: 08/03/2026
+ai-usage: ai-assisted
+---
+
+# Assembly.GetCallingAssembly behavior changes when stack trace support is disabled
+
+<xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType> now supports Native AOT and uses stack trace data to resolve the caller. If stack trace support is disabled, the method now throws <xref:System.NotSupportedException> on both Native AOT and CoreCLR.
+
+## Version introduced
+
+.NET 11 Preview 7
+
+## Previous behavior
+
+Previously, on Native AOT, <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType> always threw <xref:System.PlatformNotSupportedException>. Previously, on CoreCLR, the method returned the calling assembly even if `StackTraceSupport` was set to `false`.
+
+## New behavior
+
+Starting in .NET 11, on Native AOT, <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType> returns the calling assembly by inspecting stack trace data. Starting in .NET 11, on both Native AOT and CoreCLR, the method throws <xref:System.NotSupportedException> if `StackTrace.IsSupported` is `false`, for example when the `StackTraceSupport` feature switch is set to `false`.
+
+The exception message is:
+
+> Unable to retrieve stack trace information when StackTraceSupport feature switch is set to false.
+
+## Type of breaking change
+
+This change is a [behavioral change](../../categories.md#behavioral-change).
+
+## Reason for change
+
+To return a correct caller, <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType> requires stack trace data. If stack trace support is unavailable, the runtime can't determine the caller reliably. The runtime now throws <xref:System.NotSupportedException> instead of returning an incorrect result. For Native AOT support details, see [dotnet/runtime#129963](https://github.com/dotnet/runtime/pull/129963).
+
+## Recommended action
+
+If you publish with `StackTraceSupport` set to `false` and your app calls <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType>, expect <xref:System.NotSupportedException>. Use one of these options:
+
+- Enable stack trace support by removing the switch or setting `StackTraceSupport` to `true`.
+- Remove calls to <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType>.
+- Catch <xref:System.NotSupportedException> and handle the fallback path explicitly.
+
+## Affected APIs
+
+- <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=fullName>

docs/core/compatibility/toc.yml

@@ -10,6 +10,8 @@ items:
             href: 11.md
           - name: Core .NET libraries
             items:
+              - name: Assembly.GetCallingAssembly behavior change when stack-trace support disabled
+                href: core-libraries/11/assembly-getcallingassembly-stacktracesupport-disabled.md
               - name: CborReader and CborWriter enforce a default maximum nesting depth
                 href: core-libraries/11/cbor-max-depth.md
               - name: CRC32 validation added when reading ZIP archive entries

docs/core/deploying/trimming/trimming-options.md

@@ -77,7 +77,7 @@ Several feature areas of the framework libraries come with trimmer directives th
 | `MetadataUpdaterSupport` | When set to `false`, removes metadata update–specific logic related to hot reload. |
 | `MetricsSupport` | When set to `false`, removes support for <xref:System.Diagnostics.Metrics> instrumentation. |
 | `StackTraceLineNumberSupport` (.NET 11+) | (`PublishAot` only.) When set to `true`, generates additional line number information in the output executable module. Stack traces (for example, <xref:System.Environment.StackTrace?displayProperty=nameWithType> and <xref:System.Exception.ToString*?displayProperty=nameWithType>) will include information about file names and line numbers at runtime. This information is similar to the information generated into debugging symbol files (PDB/DWO/dSYM files). However, for apps published with `PublishAot`, the runtime doesn't read the native symbol files and the debugging symbols are only used by debuggers. |
-| `StackTraceSupport` (.NET 8+) | When set to `false`, removes support for generating stack traces (for example, <xref:System.Environment.StackTrace?displayProperty=nameWithType> or <xref:System.Exception.ToString*?displayProperty=nameWithType>) by the runtime. The amount of information that is removed from stack trace strings might depend on other deployment options. This option does not affect stack traces generated by debuggers. |
+| `StackTraceSupport` (.NET 8+) | When set to `false`, removes support for generating stack traces (for example, <xref:System.Environment.StackTrace?displayProperty=nameWithType> or <xref:System.Exception.ToString*?displayProperty=nameWithType>) by the runtime. Methods that require stack trace data, such as <xref:System.Reflection.Assembly.GetCallingAssembly?displayProperty=nameWithType>, throw <xref:System.NotSupportedException> in .NET 11 and later when this option is `false`. The amount of information that is removed from stack trace strings might depend on other deployment options. This option does not affect stack traces generated by debuggers. |
 | `UseNativeHttpHandler` | When set to `true`, uses the default platform implementation of <xref:System.Net.Http.HttpMessageHandler> for Android and iOS and removes the managed implementation. |
 | `UseSizeOptimizedLinq` (.NET 10+) | When set to `true`, removes some of the throughput optimizations in LINQ that adversely affect the size of the application. Defaults to `true` with `PublishAot`; it might not be possible to natively compile some applications with this property set to `false`. |
 | `UseSystemResourceKeys` | When set to `true`, strips exception messages for `System.*` assemblies. When an exception is thrown from a `System.*` assembly, the message is a simplified resource ID instead of the full message. |