How do I check Data Guard apply lag?

Query V$DATAGUARD_STATS and review the Apply Lag value.

How do I check Data Guard transport lag?

Query V$DATAGUARD_STATS and review the Transport Lag value.

How do I detect archive gaps?

Use SELECT * FROM V$ARCHIVE_GAP.

What is RMAN Backup Validation?

RMAN Backup Validation verifies Oracle backup integrity and recoverability without performing a restore.

What does RESTORE DATABASE VALIDATE do?

It verifies that RMAN backups can be restored successfully without actually restoring files.

How do I detect Oracle block corruption?

Use V$DATABASE_BLOCK_CORRUPTION and RMAN VALIDATE DATABASE CHECK LOGICAL.

What are the most important Oracle DBA interview topics?

Oracle Architecture, RMAN, Backup and Recovery, Data Guard, RAC, Performance Tuning, Security, and Troubleshooting are the most important Oracle DBA interview topics.

Is Oracle DBA still a good career in 2026?

Yes. Oracle DBA remains a strong career path due to the widespread use of Oracle databases in enterprise environments.

What Oracle version should I learn in 2026?

Oracle 19c and Oracle 23ai are the most valuable Oracle database versions to learn in 2026.

Requested URL/OA_HTML/AppsLogin was not found on this server

Applies to:

Oracle Enterprise Linux 5.5

Oracle Application Install - Version: 12.1.1
Database 11gR1

Description:

I recently came across a problem the login page was throwing an error - 404 /OA_HTML/AppsLogin was not found on this server. All services of Database and Listener working fine and get connected. All Application services started successfully without any error/warning on status 0, multiple time restart the services of application and database and also restart the whole machine but still facing the same problem.

Solution:

After some research work I have found the following solution:

The Problem occurs because the wsrp_service.wsdl was owned by root but the services were being started by applmgr.

Ensure that the permission of the file
$ORA_CONFIG_HOME/10.1.3/j2ee/oacore/application-deployments/oacore/html/server-wsdl/wsrp_service.wsdl

Shows that it is owned by root user. Somebody started the services of Apps as root user.
Changed the ownership of the file to Apps Owner.
Restart the service, everything working fine now.

👉 Check our complete guide: Oracle Error Codes Guide

Author Box

About the Author

Rana Abdul Wahid is an experienced Oracle Database Administrator with expertise in Oracle Database Administration, Oracle Data Guard, RMAN Backup & Recovery, Oracle RAC, Oracle E-Business Suite, Performance Tuning, and High Availability Solutions.

Through this blog, he shares practical Oracle DBA solutions, troubleshooting guides, interview preparation resources, and production-tested best practices for database professionals worldwide.

3 comments:

AnonymousFebruary 5, 2013 at 3:05:00 AM GMT+5
Thanks your post saved my job ;)
RanadheerMarch 23, 2013 at 11:36:00 AM GMT+5
hi
can you tell me steps to change the ownership to apps.
thnks in advnce
Rana Abdul WahidMarch 25, 2013 at 10:54:00 AM GMT+5
Hi,

To change the ownership of a single file:
suppose my file name is test.ora and group is oinstall and I want to change the ownership from root to apps user:

chown apps:oinstall test.ora

To change the ownership of a folder:
my folder name is /d01 and want to change the ownership of /d01 and all it's subfolders and files from root to apps user:

chown -R apps:oinstall /d01