APP-PO-14142: get_po_parameters-10: ORA-01422 When Open Purchasing Form

Problem

Following Error Occur when open a purchasing form

Solution

1. Connect apps user and run below query.

select object_name,policy_name, package,function,enable
from sys.all_policies
where object_name = upper('PO_DOCUMENT_TYPES_B')
union
select object_name,policy_name, package,function,enable
from sys.all_policies
where object_name = upper('PO_DOCUMENT_TYPES_TL')
union
select object_name,policy_name, package,function,enable
from sys.all_policies
where object_name = upper('PO_SYSTEM_PARAMETERS')
union
select object_name,policy_name, package,function,enable
from sys.all_policies
where object_name = upper('FINANCIALS_SYSTEM_PARAMETERS');

If query does not return above four policies, then add those

2. Run below script via apps user

SQL>revoke EXEMPT ACCESS POLICY from APPS;

3. Verify the issue by running following query.

select count(*) from po_document_types;

If above query return 0 rows, then issue will be resolved

Reference : 
Choosing Approval Assignments Form From Menu - Nothing Happens - Form Does Not Open (Doc ID 1063223.1)