DBUA failing with ORA-00823 ORA-01078 followed by ORA-01034

In the process of upgrading 10.2.0.4 database to 11.2.0.2, got below error when dbua tried to start the database instance using 11g binaries:

Background:
This database has below parameters EXPLICITLY set
sga_max_size 500M
sga_target 500M


Output of Pre-Upgrade tool:
I had run pre-upgrade tool(utlu112i.sql), before starting dbua. It showed me:

..
..
--> If Target Oracle is 64-Bit, refer here for Update Parameters:                                
WARNING: --> "sga_target" needs to be increased to at least 708 MB                              
..
..

DBUA:
DBUA takes care of changing the values. So I did not attempt to modify it manually.

And dbua did change for sga_target.

DBUA apparently changed value of "sga_target" to 708MB but did not change the value of "sga_max_size" accordingly.

Its a known fact that if sga_max_size can not be set lower than sga_target.

Now when dbua tried to start the instance after changing JUST sga_target , it threw ORA-00823.

If you are thinking ignore might work, then its wrong. Because the upgrade would eventually fail with ORA-01034 because dbua was not able to start the instance at first place.

Resolution:

1. You will have to Abort the upgrade.
2. Remove sga_max_size from your pfile. If you are using spfile, then create pfile first.
3. Create spfile if you want to use spfile instead of pfile.
4. Restart dbua.