After upgrading your vApp (Virtual Appliance) system to 14.4 during the migration from CentOS6 to CentOS8, you are unable to start your User Store. Looking at the ALARM log, you may see the following error:
 20220901.162213.992 DSA_I3420 The DXgrid .db file failed to load as it contains the object identifier '(22.214.171.124.4.1.7126.96.36.199.3.6485.1.9)' which is not defined in the directory schema. If using a copy of the .db file, please ensure the schema used by the DSA matches where the .db file was sourced.
 20220901.162213.992 DSA_E1280 Error in initialization files
 20220901.162213.992 DSA_I1240 DSA shutting down
Release : 14.1
Component : CA Directory
The above error message is logged (as it clearly outlines) as there is data within the DSA (in the .db file) while the actual schema file is not present in the configuration.
Your problem have the 'im_user_aux.dxc' schema file with zero bytes (blank) under $DXHOME/config/schema folder on the new CentOS8 system. On the old system you may have extended your schema as described in product documentation at:
To address this, simply copy the content of 'im_user_aux.dxc' from CentOS6 (or any other working node) to this problem CentOS8 node and your User Store should start successfully as normal.