2269231 - Software Update Manager (SUM) Error in the phase: PREP_INPUT_CHECK/READCVERS_DUMP

Software Update Manager (SUM) fails in the step: PREP_INPUT_CHECK/READCVERS_DUMP

The log file READCVERSD.LOG in DIR_PUT/log has the below error

2 ETQ399 Requested task ID is 'READ_CVERS'.
3 ETQ399 Generated TQL file 'CVERSDUMP.TQL' with 2 SQL statements, log file 'CVERSDUMP.TMP'.
4 ETQ276 Executing SQL-script "CVERSDUMP.TQL"
3 ETQ120 20160101043625: PID 8192216 execute '/usr/sap/trans/SUM/SUM/abap/bin/SAPuptool execdb ../var/CVERSDUMP.TQL', output written to '/usr/sap/trans/SUM/SUM/abap/log/SQLSTMTSTD.OUT'.
3WETQ122 20160101043625: PID 8192216 exited with status 20 (time: 0.000/0.011/0.025 real/usr/sys)
1EETQ399 Last error code set is: Process /usr/sap/trans/SUM/SUM/abap/bin/SAPuptool exited with 20, see '/usr/sap/trans/SUM/SUM/abap/log/SQLSTMTSTD.OUT' for details
1EETQ204 Upgrade phase "READCVERS_DUMP" aborted with severe errors ("20160101043625")

The log file SQLSTMTSTD.OUT in DIR_PUT/log has the below error:

EXECUTING /usr/sap/trans/SUM/SUM/abap/bin/SAPuptool execdb ../var/CVERSDUMP.TQL
Logging to '/usr/sap/trans/SUM/SUM/abap/log/CVERSDUMP.TMP'

FATAL ERROR: DBSL error 99 (db code -1): Connect failed
SAPup> Process with PID 8192216 terminated with status 20 at 20160101043625!

Update / Upgrade of NW ABAP with SUM on Oracle Database

PREP_INPUT_CHECK/READCVERS_DUMP, READCVERS_DUMP, READCVERSD.LOG, CVERSDUMP.TMP, SQLSTMTSTD.OUT, "DBSL error 99 (db code -1): Connect failed"   , KBA , BC-UPG-TLS-TLA , Upgrade tools for ABAP , Problem