Even though there is a document about up-gradation at Oracle, I wrote what I thought I will be following in future. There are things which one may not find in documents but learn with experience or when actually doing it.

Steps to up-gradation are as follows:

1. Change your working directory to apex where you have unzip the installation.

2. Start SQL*Plus from here and connect to the database as SYSDBA role. Thus making apex as your working directory.

3. To Install Full development environment
tablespace_apex tablespace_files tablespace_temp images

it can be something like this

SYSAUX SYSAUX TEMP /i/

To Install Runtime environment.

tablespace_apex tablespace_files tablespace_temp images

it can be something like this

SYSAUX SYSAUX TEMP /i/

Where:

tablespace_apex is the name of the tablespace for the Oracle Application Express application user.

tablespace_files is the name of the tablespace for the Oracle Application Express files user.

tablespace_temp is the name of the temporary tablespace.

images is the virtual directory for Oracle Application Express images.
Important Notes:

• Define the virtual image directory as /i/ to support future Oracle Application Express upgrades.
• Increase the SYSTEM tablespace otherwise you may see following error.

Once you complete the the above steps, you need to perform the following steps to complete the upgrade:

Connect as a SYSDBA

Run apxldimg.sql as follows (this will update images):
/apex/apxldimg.sql UNZIP_DIR

Run apxxepwd.sql to reinitialize the ADMIN password.
/apex/apxxepwd.sql password

Where:
password is the password of the Application Express internal ADMIN account

UNZIP_DIR is the directory where you unzip your application express installation.

When logging into Application Express 3.1 in Oracle Database XE, you will now be presented with a login page that prompts for Workspace, Username and Password.

The Workspace name is equal to the database username used to login to Oracle Database XE.

For example, in Oracle Database XE, if you used credentials Username=SCOTT, Password=TIGER, in Application Express 3.1, you will now use Workspace=SCOTT, Username=SCOTT, Password=TIGER.