Move hardcoded error strings in RemoveRegisterAttribute and GenerateCompressedAssembliesNativeSourceFiles to Properties.Resources

Documentation/docs-mobile/messages/index.md

@@ -157,6 +157,8 @@ Either change the value in the AndroidManifest.xml to match the $(SupportedOSPla
 + [XA2000](xa2000.md): Use of AppDomain.CreateDomain() detected in assembly: {assembly}. .NET 6 will only support a single AppDomain, so this API will no longer be available in .NET for Android once .NET 6 is released.
 + [XA2001](xa2001.md): Source file '{filename}' could not be found.
 + [XA2002](xa2002.md): Can not resolve reference: \`{missing}\`, referenced by {assembly}. Perhaps it doesn't exist in the .NET for Android profile?
++ [XA2024](xa2024.md): Unable to load assembly '{assembly}'.
++ [XA2025](xa2025.md): Assembly {assembly} does not exist.
 + XA2006: Could not resolve reference to '{member}' (defined in assembly '{assembly}') with scope '{scope}'. When the scope is different from the defining assembly, it usually means that the type is forwarded.
 + XA2007: Exception while loading assemblies: {exception}
 + XA2008: In referenced assembly {assembly}, Java.Interop.DoNotPackageAttribute requires non-null file name.

Documentation/docs-mobile/messages/xa2024.md

@@ -0,0 +1,27 @@
+---
+title: .NET for Android error XA2024
+description: XA2024 error code
+ms.date: 05/24/2026
+f1_keywords:
+  - "XA2024"
+---
+
+# .NET for Android error XA2024
+
+## Example messages
+
+```
+error XA2024: Unable to load assembly 'Mono.Android.dll'.
+```
+
+## Issue
+
+The build task was unable to load a required framework assembly. This
+could indicate that the assembly is missing, corrupt, or otherwise
+inaccessible.
+
+## Solution
+
+Ensure the assembly exists at the expected location and is not corrupt.
+Try cleaning and rebuilding the project. If the issue persists, reinstall
+the .NET for Android workload.

Documentation/docs-mobile/messages/xa2025.md

@@ -0,0 +1,27 @@
+---
+title: .NET for Android error XA2025
+description: XA2025 error code
+ms.date: 05/24/2026
+f1_keywords:
+  - "XA2025"
+---
+
+# .NET for Android error XA2025
+
+## Example messages
+
+```
+error XA2025: Assembly path/to/MyAssembly.dll does not exist.
+```
+
+## Issue
+
+A referenced assembly could not be found on disk during the build
+process. The assembly was expected to exist but is missing from the
+output directory.
+
+## Solution
+
+Ensure all referenced assemblies are properly built and available.
+Try cleaning and rebuilding the project. Verify that no build steps
+are inadvertently deleting required assemblies.

src/Xamarin.Android.Build.Tasks/Properties/Resources.resx

@@ -516,6 +516,14 @@ Either change the value in the AndroidManifest.xml to match the $(SupportedOSPla
 {1} -  The chain of references that causes a reference to the missing assembly, with > as the separator between items. Example: `System.Memory` > `System.Buffers`
 {2} - The name of the first assembly in the chain of references. Example: System.Memory</comment>
   </data>
+  <data name="XA2024" xml:space="preserve">
+    <value>Unable to load assembly '{0}'.</value>
+    <comment>{0} - The path to the assembly that could not be loaded.</comment>
+  </data>
+  <data name="XA2025" xml:space="preserve">
+    <value>Assembly {0} does not exist.</value>
+    <comment>{0} - The path to the assembly that does not exist.</comment>
+  </data>
   <data name="XA2006" xml:space="preserve">
     <value>Could not resolve reference to '{0}' (defined in assembly '{1}') with scope '{2}'. When the scope is different from the defining assembly, it usually means that the type is forwarded.</value>
     <comment>{0} - The member name, such as a class name

src/Xamarin.Android.Build.Tasks/Tasks/GenerateCompressedAssembliesNativeSourceFiles.cs

@@ -73,7 +73,7 @@ void GenerateCompressedAssemblySources ()
 
 					var fi = new FileInfo (assembly.ItemSpec);
 					if (!fi.Exists) {
-						Log.LogError ($"Assembly {assembly.ItemSpec} does not exist");
+						Log.LogCodedError ("XA2025", Properties.Resources.XA2025, assembly.ItemSpec);
 						continue;
 					}
 

src/Xamarin.Android.Build.Tasks/Tasks/RemoveRegisterAttribute.cs

@@ -31,7 +31,7 @@ public override bool RunTask ()
 
 			using (var assembly = resolver.Load (mono_android)) {
 				if (assembly is null) {
-					Log.LogError ($"Unable to load assembly '{mono_android}'");
+					Log.LogCodedError ("XA2024", Properties.Resources.XA2024, mono_android);
 					return false;
 				}