Namespaces are not supported for this language version (failed BAS -> on-premise deployment)

[AustinKloske]

We are unable to deploy UI apps within our partner namespace from Business Application Studio to on-premise S/4 HANA 2023 (FPS02) instance (ie. packages set to ABAP for Cloud Development). The resulting BAS deployment error is: "Namespaces are not supported for this language version".

# yaml-language-server: $schema=https://sap.github.io/ui5-tooling/schema/ui5.yaml.json

specVersion: "3.1"
metadata:
  name: cust.packandship
type: application
builder:
  resources:
    excludes:
      - /test/**
      - /localService/**
  customTasks:
    - name: deploy-to-abap
      afterTask: generateCachebusterInfo
      configuration:
        log: 5
        target:
          destination: ABC
          url: https://systemurl.local:443
          scp: false
        app:
          name: /CUST/UI_PACKSHIP
          package: /CUST/_UI_PACKSHIP
          transport: ABCK900xxxx
        exclude:
          - /test/

I have found that the deployment runs successfully if I direct the deployment to a tier 2 package set the Standard ABAP. Why are we limited to deploying partner namesapce UI components into Standard ABAP Tier 2 packages? This is counter productive towards the SAP's movement shift partner development towards Clean Core best practices.    

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[AustinKloske · Accepted solution]

After implementing SAP Note 3489660,(Enable deployment into UI5 ABAP Repository with language version "ABAP for Cloud Development" using development namespaces) the issue is resolved.

If anyone know if all customers who install our partner add-on also need to implement this note please let me know.

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