2720531 - Incorrect message displayed in phase SPAUINFO: "No SPAU transport imported"

During the upgrade of an SAP system based on NetWeaver AS ABAP, the following message is displayed in the UI during phase SPAUINFO even though a SPAU transport was used:

In the SUM logs, a SPAU transport is shown as selected and there is a corresponding import log for the transport with a successful return code:

1. SAPupConsole.log 

SPAU Transport Request

01) * <Transport name>
02) - Own Transport Request
: <Transport name>

2. <Transport name>.<SID>

4 ETW000 End of Transport (0004).
4 ETW000 date&time: 31.10.2018 - 19:25:21
4 ETW000 21 warnings occured.
1 ETP187 R3TRANS SHADOW IMPORT
1 ETP110 end date and time : "20181031192521"
1 ETP111 exit code : "4"
1 ETP199 ######################################

• SAP NetWeaver AS ABAP
• SUM 2.0 SP02

Modification Adjustment, umodauto.lst , KBA , BC-UPG-TLS-TLA , Upgrade tools for ABAP , Problem