ORA-12162: TNS:net service name is incorrectly specified

```
root@felipeurrego2 ~]# sqlplus system/oracle@//localhost:1521/xe

SQL*Plus: Release 12.2.0.1.0 Production on Fri Jun 10 17:44:44 2022

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

ERROR:
ORA-12541: TNS:no listener


Enter user-name: sys
Enter password:
ERROR:
ORA-12162: TNS:net service name is incorrectly specified

```