On a Linux AE System, after having upgraded only the binaries and launching the DB Load from a 21.x to another 21.x version, the newer version WP refuses to start and fails with this error in smgr log:
<Automation_Engine_path>/bin/ucsrvwp: symbol lookup error: libucuser_r.so: undefined symbol: _ZN7automic4util7OnLeaveD1Ev
If the library libucuser_r.so is replaced with the old one from bin folder, then it starts correctly.
Component: Automation Engine
The <automic_path>/utility/bin folder (that contained the previous version binaries and libraries) had not been upgraded before the bin folder, which caused an issue as it was used in the variable LD_LIBRARY_PATH when starting the WP process.
Upgrade the utility folder before upgrading the bin folder as explained in the documentation: