Oracle pre-defined 21 system exception types

Named system exception	Cause
Access_into_null	Object Not defined
Case_not_found	if the appropriate when is not included in the case and no ELSE is set
Collection_is_null	Collection element not initialized
Curser_already_open	Cursor already open
Dup_val_on_index	Duplicate values on columns corresponding to a unique index
Invalid_cursor	operation on an illegal cursor
Invalid_number	Inline SQL statements cannot convert characters to numbers
no_data_found	"   does not return rows, or when an element that is not initialized by the index table is applied sql aggregate functions, such as AVG and SUM, Can always return a value or null, so a SELECT INTO statement that calls an aggregate function never throws a no_ Data_found exception. fetch statements end up with no data. When this happens, no exception is thrown
Too_many_rows	When you execute a SELECT INTO, the result set exceeds one row
Zero_divide	Divisor is 0
Subscript_beyond_count	element subscript exceeds The maximum value of a nested table or Varray
Subscript_outside_limit	When using a nested table or Varray, the subscript is specified as a negative number
Value_error	The variable length is not sufficient to accommodate the actual data when the value is assigned
Login_denied	An incorrect user name or password is provided when a PL/SQL application connects to an Oracle database
not_logged_on	PL/SQL applications access data without connecting to the Oralce database
Program_error	PL/SQL internal issues, you may need to reload the data dictionary & pl./sql System Package
Rowtype_mismatch	The host cursor variable is incompatible with the return type of the PL/SQL cursor variable
Self_is_null	Call an object method on a null object when using an object type
Storage_Error	out of memory space when you run PL/SQL
sys_invalid_id	Invalid ROWID string
Timeout_on_resource	Oracle timed out while waiting for resources

Oracle pre-defined 21 system exception types