ORA-12528: TNS:listener: all appropriate instances are blocking new connections

Error:

ORA-12528: TNS:listener: all appropriate instances are blocking new connections

Workaround:

Add (UR = A) entry in tns entry like below


TESTS =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.34)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = tests)
     (UR = A)
    )
  )