SQL> CREATE USER testuser1 IDENTIFIED BY "Cat"2 DEFAULT TABLESPACE users3 TEMPORARY TABLESPACE temp;User created. SQL> CREATE USER testuser2 IDENTIFIED BY "H@t" 2 DEFAULT TABLESPACE users 3 TEMPORARY TABLESPACE temp; User created. SQL> GRANT create session TO testuser1, testuser2; Grant sUCceeded. SQL> connect testuser1/cat Connected. SQL> connect testuser2/h@t ERROR: ORA-12154: TNS:could not resolve the connect identifier specified Warning: You are no longer connected to ORACLE. SQL> connect testuser2/"h@t" Connected. SQL> The workaround is to enclose the password in quotes, as shown in the listing.