ORA-00001: unique constraint XXXXXXX violated
ORA-06512: at “XXXXXXXXX”, line 5
ORA-04088: error during execution of trigger ‘TRRIGER_ NAME’

This is mostly because trrigger is in use. This error will be reported if it performs merge into operation or inserts or updates the target table.

Solution: close trrigger and execute merge into, insert and update statements.

alter trigger trriger_name disable;

After executing the statement, turn on trrigger.

alter trigger trriger_name enable;

Disadvantages:

Data loss may occur between disable and enable.