Add searched .NET install locations to error message (#117796)

elinor-fung · web-flow · commit e7683588bc98 · 2025-07-21T08:15:59.000-07:00
Include searched locations in error message when host cannot find a .NET install (`hostfxr`) Example - the 'following locations were searched' section is new: ``` You must install .NET to run this application. App: /home/repos/helloworld/bin/Debug/net10.0/helloworld Architecture: x64 App host version: 10.0.0-dev .NET location: Not found The following locations were searched: Application directory: /home/repos/helloworld/bin/Debug/net10.0/ Environment variable: DOTNET_ROOT_X64 = <not set> DOTNET_ROOT = <not set> Registered location: /etc/dotnet/install_location_x64 = <not set> Default location: /usr/share/dotnet Learn more: https://aka.ms/dotnet/app-launch-failed Download the .NET runtime: https://aka.ms/dotnet-core-applaunch?missing_runtime=true&arch=x64&rid=linux-x64&os=ubuntu.22.04&apphost_version=10.0.0-dev ```
diff --git a/src/installer/tests/HostActivation.Tests/InstallLocation.cs b/src/installer/tests/HostActivation.Tests/InstallLocation.cs
@@ -322,6 +322,51 @@ public void RegisteredInstallLocation_DotNetInfo_ListOtherArchitectures()
             }
         }
 
+        [Fact]
+        public void NotFound()
+        {
+            TestApp app = sharedTestState.TestBehaviourEnabledApp;
+
+            // Ensure no install locations are registered
+            using (var registeredInstallLocationOverride = new RegisteredInstallLocationOverride(app.AppExe))
+            {
+                string defaultLocation = Path.GetTempPath();
+                string registeredLocationOverride = OperatingSystem.IsWindows() // Host uses short form of base key for Windows
+                    ? registeredInstallLocationOverride.PathValueOverride.Replace(Microsoft.Win32.Registry.CurrentUser.Name, "HKCU")
+                    : registeredInstallLocationOverride.PathValueOverride;
+                Command.Create(app.AppExe)
+                    .CaptureStdOut()
+                    .CaptureStdErr()
+                    .ApplyRegisteredInstallLocationOverride(registeredInstallLocationOverride)
+                    .EnvironmentVariable(Constants.TestOnlyEnvironmentVariables.DefaultInstallPath, defaultLocation)
+                    .DotNetRoot(null)
+                    .Execute()
+                    .Should().Fail()
+                    .And.HaveStdErrContaining("The following locations were searched:")
+                    .And.HaveStdErrContaining(
+                        $"""
+                          Application directory:
+                            {app.Location}
+                        """)
+                    .And.HaveStdErrContaining(
+                        $"""
+                          Environment variable:
+                            DOTNET_ROOT_{TestContext.BuildArchitecture.ToUpper()} = <not set>
+                            DOTNET_ROOT = <not set>
+                        """)
+                    .And.HaveStdErrMatching(
+                        $"""
+                          Registered location:
+                            {System.Text.RegularExpressions.Regex.Escape(registeredLocationOverride)}.*{TestContext.BuildArchitecture}.* = <not set>
+                        """)
+                    .And.HaveStdErrContaining(
+                        $"""
+                          Default location:
+                            {defaultLocation}
+                        """);
+            }
+        }
+
         [Theory]
         [InlineData(SearchLocation.AppLocal)]
         [InlineData(SearchLocation.AppRelative)]
diff --git a/src/native/corehost/apphost/standalone/hostfxr_resolver.cpp b/src/native/corehost/apphost/standalone/hostfxr_resolver.cpp
@@ -121,6 +121,7 @@ hostfxr_resolver_t::hostfxr_resolver_t(const pal::string_t& app_root)
     else if (!pal::is_path_fully_qualified(m_fxr_path))
     {
         // We should always be loading hostfxr from an absolute path
+        trace::error(_X("Path to %s must be fully qualified: [%s]"), LIBFXR_NAME, m_fxr_path.c_str());
         m_status_code = StatusCode::CoreHostLibMissingFailure;
     }
     else if (pal::load_library(&m_fxr_path, &m_hostfxr_dll))
diff --git a/src/native/corehost/corehost.cpp b/src/native/corehost/corehost.cpp
@@ -212,10 +212,7 @@ int exe_start(const int argc, const pal::char_t* argv[])
     // Obtain the entrypoints.
     int rc = fxr.status_code();
     if (rc != StatusCode::Success)
-    {
-        trace::error(_X("Failed to resolve %s [%s]. Error code: 0x%x"), LIBFXR_NAME, fxr.fxr_path().empty() ? _X("not found") : fxr.fxr_path().c_str(), rc);
         return rc;
-    }
 
 #if defined(FEATURE_APPHOST)
     if (bundle_marker_t::is_bundle())
diff --git a/src/native/corehost/fxr_resolver.cpp b/src/native/corehost/fxr_resolver.cpp
@@ -93,7 +93,6 @@ bool fxr_resolver::try_get_path(
     bool search_app_relative = (search & search_location_app_relative) != 0 && app_relative_dotnet_root != nullptr && !app_relative_dotnet_root->empty();
     bool search_env = (search & search_location_environment_variable) != 0;
     bool search_global = (search & search_location_global) != 0;
-    pal::string_t default_install_location;
     pal::string_t dotnet_root_env_var_name;
     if (search_app_relative && pal::fullpath(app_relative_dotnet_root))
     {
@@ -111,10 +110,11 @@ bool fxr_resolver::try_get_path(
     }
     else if (search_global)
     {
-        if (pal::get_dotnet_self_registered_dir(&default_install_location) || pal::get_default_installation_dir(&default_install_location))
+        pal::string_t global_install_location;
+        if (pal::get_dotnet_self_registered_dir(&global_install_location) || pal::get_default_installation_dir(&global_install_location))
         {
-            trace::info(_X("Using global install location [%s] as runtime location."), default_install_location.c_str());
-            out_dotnet_root->assign(default_install_location);
+            trace::info(_X("Using global install location [%s] as runtime location."), global_install_location.c_str());
+            out_dotnet_root->assign(global_install_location);
         }
         else
         {
@@ -130,35 +130,7 @@ bool fxr_resolver::try_get_path(
         return get_latest_fxr(std::move(fxr_dir), out_fxr_path);
 
     // Failed to find hostfxr
-    if (trace::is_enabled())
-    {
-        trace::verbose(_X("The required library %s could not be found. Search location options [0x%x]"), LIBFXR_NAME, search);
-        if (search_app_local)
-            trace::verbose(_X("  app-local: [%s]"), root_path.c_str());
-
-        if (search_app_relative)
-            trace::verbose(_X("  app-relative: [%s]"), app_relative_dotnet_root->c_str());
-
-        if (search_env)
-            trace::verbose(_X("  environment variable: [%s]"), dotnet_root_env_var_name.c_str());
-
-        if (search_global)
-        {
-            if (default_install_location.empty())
-            {
-                pal::get_dotnet_self_registered_dir(&default_install_location);
-            }
-            if (default_install_location.empty())
-            {
-                pal::get_default_installation_dir(&default_install_location);
-            }
-
-            pal::string_t self_registered_config_location = pal::get_dotnet_self_registered_config_location(get_current_arch());
-            trace::verbose(_X("  global install location [%s]\n  self-registered config location [%s]"),
-                default_install_location.c_str(),
-                self_registered_config_location.c_str());
-        }
-    }
+    trace::verbose(_X("The required library %s could not be found. Search location options [0x%x]"), LIBFXR_NAME, search);
 
     pal::string_t host_path;
     pal::get_own_executable_path(&host_path);
@@ -187,6 +159,66 @@ bool fxr_resolver::try_get_path(
         }
     }
 
+    pal::string_t searched_locations = _X("The following locations were searched:");
+    if (search_app_local && !root_path.empty())
+    {
+        searched_locations.append(_X("\n  Application directory:\n    "));
+        searched_locations.append(root_path);
+    }
+
+    if (search_app_relative)
+    {
+        searched_locations.append(_X("\n  App-relative location:\n    "));
+        searched_locations.append(*app_relative_dotnet_root);
+    }
+
+    if (search_env)
+    {
+        searched_locations.append(_X("\n  Environment variable:\n    "));
+        if (dotnet_root_env_var_name.empty())
+        {
+            searched_locations.append(get_dotnet_root_env_var_for_arch(get_current_arch()));
+            searched_locations.append(_X(" = <not set>\n    "));
+            searched_locations.append(DOTNET_ROOT_ENV_VAR _X(" = <not set>"));
+        }
+        else
+        {
+            searched_locations.append(dotnet_root_env_var_name);
+            searched_locations.append(_X(" = "));
+            searched_locations.append(*out_dotnet_root);
+        }
+    }
+
+    // Global locations are only searched if environment variables are not set
+    if (search_global && dotnet_root_env_var_name.empty())
+    {
+        searched_locations.append(_X("\n  Registered location:\n    "));
+        searched_locations.append(pal::get_dotnet_self_registered_config_location(get_current_arch()));
+
+        pal::string_t self_registered_dir;
+        if (pal::get_dotnet_self_registered_dir(&self_registered_dir) && !self_registered_dir.empty())
+        {
+            searched_locations.append(_X(" = "));
+            searched_locations.append(self_registered_dir);
+        }
+        else
+        {
+            searched_locations.append(_X(" = <not set>"));
+        }
+
+        // Default install location is only searched if self-registered location is not set
+        if (self_registered_dir.empty())
+        {
+            pal::string_t default_install_location;
+            pal::get_default_installation_dir(&default_install_location);
+            searched_locations.append(_X("\n  Default location:\n    "));
+            searched_locations.append(default_install_location);
+        }
+    }
+
+    location.append(_X("\n\n"));
+    location.append(searched_locations);
+
     trace::error(
         MISSING_RUNTIME_ERROR_FORMAT,
         INSTALL_NET_ERROR_MESSAGE,
diff --git a/src/native/corehost/hostmisc/utils.cpp b/src/native/corehost/hostmisc/utils.cpp
@@ -360,23 +360,33 @@ pal::string_t get_dotnet_root_env_var_for_arch(pal::architecture arch)
 
 bool get_dotnet_root_from_env(pal::string_t* dotnet_root_env_var_name, pal::string_t* recv)
 {
-    *dotnet_root_env_var_name = get_dotnet_root_env_var_for_arch(get_current_arch());
-    if (get_file_path_from_env(dotnet_root_env_var_name->c_str(), recv))
+    pal::string_t env_var_name = get_dotnet_root_env_var_for_arch(get_current_arch());
+    if (get_file_path_from_env(env_var_name.c_str(), recv))
+    {
+        *dotnet_root_env_var_name = env_var_name;
         return true;
+    }
 
 #if defined(WIN32)
     if (pal::is_running_in_wow64())
     {
-        *dotnet_root_env_var_name = _X("DOTNET_ROOT(x86)");
-        if (get_file_path_from_env(dotnet_root_env_var_name->c_str(), recv))
+        if (get_file_path_from_env(_X("DOTNET_ROOT(x86)"), recv))
+        {
+            *dotnet_root_env_var_name = _X("DOTNET_ROOT(x86)");
             return true;
+        }
     }
 #endif
 
     // If no architecture-specific environment variable was set
     // fallback to the default DOTNET_ROOT.
-    *dotnet_root_env_var_name = DOTNET_ROOT_ENV_VAR;
-    return get_file_path_from_env(dotnet_root_env_var_name->c_str(), recv);
+    if (get_file_path_from_env(DOTNET_ROOT_ENV_VAR, recv))
+    {
+        *dotnet_root_env_var_name = DOTNET_ROOT_ENV_VAR;
+        return true;
+    }
+
+    return false;
 }
 
 /**

Original file line number	Diff line number	Diff line change
`@@ -121,6 +121,7 @@ hostfxr_resolver_t::hostfxr_resolver_t(const pal::string_t& app_root)`
`121`	`121`	`else if (!pal::is_path_fully_qualified(m_fxr_path))`
`122`	`122`	`{`
`123`	`123`	`// We should always be loading hostfxr from an absolute path`
	`124`	`+ trace::error(_X("Path to %s must be fully qualified: [%s]"), LIBFXR_NAME, m_fxr_path.c_str());`
`124`	`125`	`m_status_code = StatusCode::CoreHostLibMissingFailure;`
`125`	`126`	`}`
`126`	`127`	`else if (pal::load_library(&m_fxr_path, &m_hostfxr_dll))`