Error:

 Login page not coming  in R12 and In oacore log I observed below error

 <[136] oracle.apps.fnd.framework.OAException: Application: FND, Message Name: FND_NO_TRANSACTION_ID.
        at oracle.apps.fnd.framework.webui.OAJSPHelper.getTransactionId(OAJSPHelper.java:352)
        at oracle.apps.fnd.framework.webui.OAJSPApplicationRegistry.registerApplicationModule(OAJSPApplicationRegistry.java:133)
        at oracle.apps.fnd.framework.webui.OAJSPApplicationRegistry.registerApplicationModule(OAJSPApplicationRegistry.java:78)
        at oracle.apps.fnd.framework.webui.OAPageBean.preparePage(OAPageBean.java:1324)
        at oracle.apps.fnd.framework.webui.OAPageBean.preparePage(OAPageBean.java:567)
        at oracle.apps.fnd.framework.webui.OAPageBean.preparePage(OAPageBean.java:455)


 To implement the solution, execute the following steps:

 Solution 1:

 1. Check for any invalid objects in the database instance, by running for instance the following sql statements as a DBA user in sqlplus:

 select owner, object_type, count(*)
from dba_objects
where status='INVALID'
group by owner, object_type;

 select owner, object_name
from dba_objects
where status='INVALID'
order by owner;
Please reference Note 1325394.1 to address any invalid objects.
2. Run adadmin to compile the APPS schema:
3. Check for tablespaces free space, by running for instance the following sql statement as a DBA user in sqlplus:
select Total.name "Tablespace Name", nvl(Free_space, 0) Free_space,
nvl(total_space-Free_space, 0) Used_space, total_space
from
 (select tablespace_name, sum(bytes/1024/1024) Free_Space
  from sys.dba_free_space
  group by tablespace_name) Free,
  (select b.name, sum(bytes/1024/1024) TOTAL_SPACE
   from sys.v_$datafile a, sys.v_$tablespace B
   where a.ts# = b.ts#
   group by b.name) Total
where Free.Tablespace_name(+) = Total.name
order by Total.name;
4. Ask the DBA to add space for the corresponding full tablespaces.

 OR

 Solution 2
Per Bug 17162246 : RANDOM ERROR FND_NO_TRANSACTION_ID WHILE OPENING VIEW DOCUMENT PAGE
 Please follow the below steps to schedule a concurrent request to purge the
 inactive sessions periodically (once in a week for high traffic instances):
 1. Log in using sysadmin.
 2. Navigate to Self Service Web Applications Manager, Vision Enterprises -->
 Requests --> Run
 3. In the Form that opens run/schedule "Purge Inactive Sessions" request.   This internally clears of the icx_transactions table entries also.

It is generally recommended to schedule "Purge Inactive Sessions" concurrent request to run at least weekly, but some high volume customers find it necessary to run on a more regular basis - nightly. This request runs the script $ICX_TOP/sql/ICXDLTMP.sql which deletes any information in ICX_SESSIONS (and its dependent tables) that is more than 4 hours old and alleviates the performance issues associated with letting these tables grow with obsolete data.
If the "Purge Inactive Sessions" request does not exist in your R12 instance, please review Note: 397118.1 Where Is 'Delete Data From Temporary Table' Concurrent Program - ICXDLTMP.SQL
Ref:Can Not Login To The Applications: oracle.apps.fnd.framework.OAException: FND_NO_TRANSACTION_ID error (Doc ID 737960.1)