ORA-01653 error while upgrading APEX from 4.2 to 5.0 and Application Express is already installed (APEX_050000)

Trying to upgrading from 4.2 to 5.0

Steps followed

- Initiated @apexins.sql APEX SYSAUX TEMP /i/ 
- In the middle of the upgrade I got failed due to 
ERROR at line 1: 
ORA-01653: unable to extend table APEX_050000.WWV_FLOW_UPGRADE_PROGRESS by 8 in 
tablespace APEX 
ORA-06512: at "APEX_050000.WWV_FLOW_UPGRADE", line 973 
ORA-06512: at "APEX_050000.WWV_FLOW_UPGRADE", line 1659 
ORA-01658: unable to create INITIAL extent for segment in tablespace APEX 
ORA-06512: at "APEX_050000.WWV_FLOW_UPGRADE", line 3715 
ORA-06512: at line 4 

- I have added more space to APEX 
- Now tried to initiated @apexins.sql APEX SYSAUX TEMP /i/ but I got Error: This version of Application Express is already installed (APEX_050000). 


How to fix this issue? 

• I am getting "Error: This version of Application Express is already installed" error when i am re initiating apex upgrade, so commented "execute immediate 'bogus statement to force exit';" line in "apxprereq.sql" 

• Next I got "ORA-01920: user name 'APEX_040200' conflicts with another user or role name", this time commented "create user ^APPUN identified by "^ADM_PWD" password expire account lock default tablespace ^DATTS temporary tablespace ^TEMPTBL;" line in "coreins.sql" 

• Now initiate upgrade using "@apexins.sql APEX SYSAUX TEMP /i/" 

Everything went fine. And all existing applications working fine with new look and feel in APEX5.