Oracle - Unable to extend index SYS.I_OBJ1 by 8 in tablespace SYSTEM

If you see the following similar error message

unable to extend index SYS.I_OBJ1 by 8 in tablespace SYSTEM

It means that your tablespace is out of space and you should increase it if possible.

You can issue the following command to check your current size of the tablespace

select * from dba_data_files where tablespace_name='SYSTEM';

It will return the path and the current size of the tablespace

The above should that I have only about 650M tablespace.

Then, depend on your current size, you could issue the following 

alter database datafile '/u01/app/oracle/oradata/XE/system.dbf' resize 1024M

Note: The above example is increasing to 1024M to my path. You should modify the path and size according to your need.

Reference:

1. http://www.markcallen.com/oracle/ora-01654-unable-to-extend-index/