ORA-00055: Maximum Number of DML locks exceeded
The number of DML Locks is set by the initialization parameter DML_LOCKS. If this value is set to low (which it is by default) you will get this error. Try to find the issue and if it is temporary we can leave it as such. Other wise we need to increase the value of DML_LOCKS. Some times this occurs at the moment of peak load in database.
Change in the parameter file (initSID.ora) For Example: dml_locks = 200