This will happen if you shut down the broker process (bkrd or bkrd.exe) but do not shut down the rtserver process (rtserver or rtserver.exe).
Release: SCMNCR99000-12.5-Harvest-Software Change Manager-Named User-Competitive Replacem
On Windows, check the Processes tab in Task Manager. Look for any remaining Harvest-related processes (rtserver.exe, hserver.exe, bkrd.exe, agntd.exe) and kill those.
On Linux and Unix, execute "ps -ef | grep <process name>" to look for any remaining Harvest-related processes (rtserver, hserver, bkrd, agntd). Kill any remaining processes that you find.
Be sure to search for and kill the rtserver process as a last step. If you kill the rtserver process while the broker is still running, the broker will try to initiate a new rtserver process.
CA Harvest SCM all versions and platforms