https://userapps.support.sap.com/sap/support/knowledge/en/2921961
2921961 - SUM stops at HDB_CHK_PRIVILEGES phase | SAP Knowledge Base Article
You are trying to update your S/4 HANA system using SUM. The upgrade gets stuck on the PREP_INIT/HDB_CHK_PRIVILEGES. In HDBSLLIB_CHK_PRIVILEGES.LOG you found...