2244827 - SUM or SAPup in an execution phase (e.g. PARCONV_UPG, XPRAS_AIMMRG) error: Upgrade still running: Logon not possible

SYMPTOM 1:

During a system update using Software update manager (SUM) or Sapup tool
in an execution roadmap phase (e.g. PARCONV_UPG, XPRAS_AIMMRG), you may be required to login to the Standard instance.
When you logon to the Standard instance with a user other than DDIC, 
the following error message shows at the bottom of the logon screen:

"Upgrade still running: Logon not possible"

SYMPTOM 2:

During upgrade, when modifying objects on the Standard instance  in an  execution roadmap phase (e.g. PARCONV_UPG, XPRAS_AIMMRG) using user DDIC, following error occurs:


User DDIC may not make changes in customer systems
Message no. TK691
Diagnosis
User DDIC cannot change Repository or Customizing objects in a customer system.
System Response
The function terminates and the system branches to the object display.
Procedure
Make the changes as a user with the required authorization.

System upgrade or update of NetWeaver based systems using SUM or SAPup

 FINB_TR 032, /$SYNC , tp unlocksys , KBA , xpras_upg , BC-UPG-TLS-TLA , Upgrade tools for ABAP , BC-DWB-CEX , Customer Extensions , BC-ABA , ABAP Runtime Environment - ABAP Language Issues Only , How To