Error: "Unable to Connect" Oracle Apex Access Issue

Recently we had install the Oracle Apex and installation done successfully and access via local system Oracle Apex running perfectly but while we access in remote then we had faced the problem in Oracle Apex Application running issue.

Error: Unable to Connect

Cause: APEX using the XDB protocol if you use XDB protocols and then need DISPATCHERS but we had not configure the dispatcher.

Solution: One thing to remember, if you are only using XDB services for batch processing or only for intermittent connections you can actually set DISPATCHERS dynamically and turn it on.

This is because XDB protocols like HTTP and FTP require shared server. 

Example: 

dispatchers="(PROTOCOL=TCP)(SERVICE=TESTXDB)"

LOCAL_LISTENER = "(ADDRESS=(PROTOCOL=TCP)(HOST=Hostname)(port=1528))"

How to change EBS R12 Database and Application Port Number

Recently we had faced the application port blocking issue in oracle EBS R12.
We had follow the below steps to resolve this issue...

Execute the below in Application Tier:

Run adpreclone on Application Tier
   $ perl ./adpreclone.pl appsTier

Execute the following on the Database Tier:

Logon as oracle database user and set envirnoment variable for R12 RDBMS ORACLE_HOME

Start the database instance for which you want to change R12 port

Backup contextfile

Change as below parameters values in the contextfile

        dbport  : Change database port from 1521 to 1531
        cmanport : 1521 to 1531

Run adautocfg.sh on Database Tier

And also change the port in listener.ora & tnsnames.ora file.

Again Execute the following in Application Tier:

Logon as application user and set environment variable for R12.

Backup context file

Stop all oracle services for Applications by running "adstpall.sh".

Run adcfgclone and choose new port pool
   $ cd $COMMON_TOP/clone/bin
   $ perl ./adcfgclone.pl appsTier

Check new application URL

SQL> select home_url from icx_parameters;

HOME_URL
------------------------------------------------------------
http://<hostname.domainname>:8010/OA_HTML/AppsLogin