https://userapps.support.sap.com/sap/support/knowledge/en/3739810
3739810 - IW_FND: Preparing component uninstallations failed in SUM | SAP Knowledge Base Article
Getting error in SUM phase PREP_EXTENSION/UNINSTALL_PREPARE, following error observed: ... 2 ETQ399 Preparing Component Uninstallation(s) ... 2 ETQ399 ......