ORA-00823: Specified value of sga_target greater than sga_max_size dba
I solved it as follows:


Open the pfile and set sga_target=0 and save it.
After :

create spfile from pfile;
create pfile from spfile;

Now start the database :

SQL&gt; startup

ORACLE instance started.
Total System Global Area 5133828096 bytes
Fixed Size                  8929496 bytes
Variable Size             956305192 bytes
Database Buffers         4160749568 bytes
Redo Buffers                7843840 bytes
Database mounted.
Database opened.