ORA-30036: unable to extend segment by 8 in undo tablespace

How to Resolve ORA-30036

Cause :- Undo tablespace is full.

Check how much free space availiable in UNDO tablespace

SELECT TABLESPACE_NAME,SUM(BYTES)/1024/1024/1024 "FREE SPACE(GB)"
FROM DBA_FREE_SPACE WHERE TABLESPACE_NAME='UNDOTBS1' GROUP BY TABLESPACE_NAME;

Solution:- Extend undo tablespace.

There are two possibilities

1. Add a New datafile to UNDO tablespace,

• ensure you have sufficient space under /mount_point where you are adding the datafile.
• adjust path, size, autoexend etc according to your requirement 

alter tablespace UNDOTBS1 add datafile '/ora_app/product/oradata/oemrp/undotbs02.dbf' size 100M autoextend on next 100M maxsize unlimited;

Tablespace altered.

     2.  Resize the existing datafile if possible

alter database datafile '/ora_app/product/oradata/oemrp/undotbs01.dbf' resize 1G;
Database altered.