I’ve a project that uses Xaml and C#. When trying to build it, I get the error described in the title.

Here the full error:
Severity Code Description Project File Line Suppression State
Error (active) WMC9999 Name cannot begin with the ‘ ‘ character, hexadecimal value 0x20. Line 2, position 3. BetterApp C:Usersadmin.nugetpackagesmicrosoft.windowsappsdk1.5.240404000buildTransitiveMicrosoft.UI.Xaml.Markup.Compiler.interop.targets 505

And here a little snippet of where it says where the error is:

    `<CompileXaml Condition="'$(UseXamlCompilerExecutable)' != 'true'"
                LanguageSourceExtension="$(DefaultLanguageSourceExtension)"
                Language="$(XamlLanguage)"
                RootNamespace="$(RootNamespace)"
                XamlPages="@(Page)"
                XamlApplications="@(ApplicationDefinition)"
                PriIndexName="$(PriIndexName)"
                ProjectName="$(XamlProjectName)"
                IsPass1="True"
                CodeGenerationControlFlags="$(XamlCodeGenerationControlFlags)"
                ProjectPath="$(MSBuildProjectFullPath)"
                CIncludeDirectories="$(XamlCppIncludeDirectories)"
                OutputPath="$(XamlGeneratedOutputPath)"
                OutputType="$(OutputType)"
                ReferenceAssemblyPaths="@(ReferenceAssemblyPaths)"
                ReferenceAssemblies="@(ReferencePath)"
                ForceSharedStateShutdown="False"
                CompileMode="RealBuildPass1"
                XAMLFingerprint="$(XAMLFingerprint)"
                UseVCMetaManaged="$(UseVCMetaManaged)"
                FingerprintIgnorePaths="$(XAMLFingerprintIgnorePaths)"
                VCInstallDir="$(VCInstallDir)"
                SavedStateFile="$(XamlSavedStateFilePath)"
                SuppressWarnings="$(SuppressXamlWarnings)"
                TargetPlatformMinVersion="$(TargetPlatformMinVersion)"
                WindowsSdkPath="$(WindowsSdkPath)"
                XamlResourceMapName="$(XamlResourceMapName)"
                XamlComponentResourceLocation="$(XamlComponentResourceLocation)"
                FeatureControlFlags="@(XamlFeatureControlFlags)"
                VCInstallPath32="$(VCInstallPath32)"
                VCInstallPath64="$(VCInstallPath64)"
                GenXbfPath="$(GenXbfPath)"
                PrecompiledHeaderFile="$(PrecompiledHeaderFile)" >

                <Output Condition=" '$(ManagedAssembly)'!='false' " ItemName="Compile"   TaskParameter="GeneratedCodeFiles" />

                <!--
                    FileWrites is used in Microsoft.Common.Targets for "Clean" build
                -->
                <Output ItemName="FileWrites" TaskParameter="GeneratedCodeFiles" />
                <Output ItemName="FileWrites" TaskParameter="GeneratedXamlFiles" />
                <Output ItemName="FileWrites" TaskParameter="GeneratedXbfFiles" />
                <Output ItemName="_GeneratedCodeFiles" TaskParameter="GeneratedCodeFiles" />
                <Output ItemName="_GeneratedXamlFiles" TaskParameter="GeneratedXamlFiles" />
                <Output ItemName="_GeneratedXbfFiles" TaskParameter="GeneratedXbfFiles" />
            </CompileXaml>`

I’ve reinstalled the SDK multiple times now and also created a new project. Visual Studio is freshly updated but the issue still persists.