Thanks @Roy Li - MSFT for your quick response. The followed the below steps but still facing the same issue unable to add printSupportSettingsUI Extensions
Step 1: Installed V2019 16.11.22 and installed the Multi-instance extension
Step 2. Created Sample Multi-instance UWP Application for PSA(Print Support Application). As you can see, SupportsMultipleInstances is enabled.
Step 3: Added the xmlns:printsupport="http://schemas.microsoft.com/appx/manifest/printsupport/windows10" in my Package.appxmanifest
Step 4: Added extension in my Package.appxmanifest and I am unable to add this extension for printSupportSettingsUI
<?xml version="1.0" encoding="utf-8"?>
<Package
xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
xmlns:uap10="http://schemas.microsoft.com/appx/manifest/uap/windows10/10"
xmlns:uap12="http://schemas.microsoft.com/appx/manifest/uap/windows10/12"
xmlns:printsupport="http://schemas.microsoft.com/appx/manifest/printsupport/windows10"
xmlns:desktop4="http://schemas.microsoft.com/appx/manifest/desktop/windows10/4"
xmlns:iot2="http://schemas.microsoft.com/appx/manifest/iot/windows10/2"
IgnorableNamespaces="uap uap12 mp desktop4 iot2 printsupport">
<Identity
Name="6f7dbd2e-36ce-42ec-b51e-7c0e4d34b9d9"
Publisher="CN=AKundapur"
Version="1.0.0.0" />
<mp:PhoneIdentity PhoneProductId="6f7dbd2e-36ce-42ec-b51e-7c0e4d34b9d9" PhonePublisherId="00000000-0000-0000-0000-000000000000"/>
<Properties>
<DisplayName>PSASampleApp</DisplayName>
<PublisherDisplayName>AKundapur</PublisherDisplayName>
<Logo>Assets\StoreLogo.png</Logo>
</Properties>
<Dependencies>
<TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.0.0" MaxVersionTested="10.0.0.0" />
</Dependencies>
<Resources>
<Resource Language="x-generate"/>
</Resources>
<Applications>
<Application Id="App"
Executable="$targetnametoken$.exe"
EntryPoint="PSASampleApp.App"
desktop4:SupportsMultipleInstances="true"
iot2:SupportsMultipleInstances="true">
<uap:VisualElements
DisplayName="PSASampleApp"
Square150x150Logo="Assets\Square150x150Logo.png"
Square44x44Logo="Assets\Square44x44Logo.png"
Description="PSASampleApp" BackgroundColor="transparent">
<uap:DefaultTile
Wide310x150Logo="Assets\Wide310x150Logo.png"
Square310x310Logo="Assets\Square310x310Logo.png"
Square71x71Logo="Assets\Square71x71Logo.png">
</uap:DefaultTile>
<uap:SplashScreen Image="Assets\SplashScreen.png" />
</uap:VisualElements>
<Extensions>
<printsupport:Extension Category="windows.printSupportSettingsUI"
EntryPoint="PsaSample.PsaSettingsUISample"/>
</Extensions>
</Application>
</Applications>
<Capabilities>
<Capability Name="internetClient" />
</Capabilities>
</Package>