Following error message is obtained in the app-ca.log in one of these scenarios:
ORA-01795: maximum number of expressions in a list is 1000
Error 500 appears in the UI.
In both these scenarios, the SQL that the application generates will contain an IN clause in which all the records fetched or saved in the lookup field are passed as input. Oracle has a limitation of not passing more than 1000 records in an IN clause.
Oracle limitation of 1000 values per IN clause: