3091477 - SUM phase MAIN_POSTCLEAN/TOOLIMP_DELETE_ABAP runs for long time

The system is being converted ERP system to S/4HANA using DMO with system move option.

SUM phase MAIN_POSTCLEAN/TOOLIMP_DELETE_ABAP runs for long time.

There is no error in SUM phase log PHASE_TOOLIMP_NEW.LOG.
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3 ETQ121 <time_stamp>: PID <process_ID> execute '<DRIVE>:\usr\sap\<sid>\<instance_number>\exe\tp "pf=~\var\DELABAP.TPP" import all <sid>' in background, output written to '<DRIVE>:\usr\sap\<sid>\SUM\abap\log\SAPup_NEW.ECO'.
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The following warning message can be seen in <DIR_PUT>\ABAP\log\SLOG.
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WARNING:       Background job RDDIMPDP could not be started or terminated abnormally.
      Please check that the R/3 system is running.
      Please check the system. Use transactions SM21, SM37, SM50.
WARNING:       (This warning is harmless if no further warnings follow.)
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• SAP ERP 6.0
• OS and DB independent

"MAIN_POSTCLEAN/TOOLIMP_DELETE_ABAP", "TOOLIMP_DELETE_ABAP", "SUM", "long time", "performance", "Background job RDDIMPDP could not be started or terminated abnormally" , KBA , BC-UPG-TLS-TLA , Upgrade tools for ABAP , Problem