ora-02020: too many database links in use

Error: 

ora-02020: too many database links in use

Reason:

SQL> show parameter link

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
open_links                           integer     4
open_links_per_instance              integer     4
SQL>

Solution:

ALTER SESSION CLOSE DATABASE LINK linkname;

Note that this statement only closes the links that are active in your current session. 

Increase the open_links and open_links_instance parameter in the DB . Bounce Database





alter system set open_links =20 scope =spfile;

alter system set open_links_per_instance=20 scope=spfile;

Or
SQL>alter session close database link "link name";