Form Issue

Question

Try to launch any form on 11.5.9, always get APP-FND-01508: Failed to connect.
Cause: Application Object library was unable to connect Oracle database.

Answer 1

Could you please verify that you are able to login to SQL*Plus as apps user?
If the above works fine, then looks like you have incorrect database instance name is in the database instance field in the fnd_profile_option_values table. To fix it, please do the following:
SQL> select profile_option_id from fnd_profile_options where profile_option_name like '%DATABASE%';
SQL> select profile_option_id, level_id, level_value,
profile_option_value
from fnd_profile_option_values
where profile_option_id in (<Values Returned from 1st Qurey);
SQL> update fnd_profile_option_values
set profile_option_value = '<CORRECT VALUE>'
where profile_option_value = '<INVALID VALUE>';
OR
SQL> delete from  fnd_profile_option_values
where profile_option_value = '<INVALID VALUE>';