This error occurred when password file “entries” value is reached to maximum size. So we need to do: 1. Shutdown Oracle Server 2. Recreate PASSWORD FILE with MAXIMUM ENTRIES=N VALUE. In command line >ORAPWD file={Oracle DB system path}\DATABASE\[Password File Name].ORA password=[Password] entries=[Entries Number] [Password File Name]: oracle new password-file name. [Password] : oracle system password. [Entries Number] : Maxmium entries number. 3. Restart Oracle Service After recreate PWD file. ORA-01996 & ORA-01994