TNS-12520 when connecting via TCPS on 11gR2 RAC with SCAN Listener

Question

I am struck trying to implement TCPS on our Oracle RAC SCAN Listener.  I have added to our Oracle 12c systems, but not on a RAC with SCAN.
I created a wallet and certificate on one of the nodes, and copied it to the node and created auto login on each node.  I exported the trust.jks and identity.jks, and loaded them in my test java program as the trust store and key stores.  I have added the wallet location to the listener tns and sql  ora files.
When attempting a TCPS connection, the ssl handshake succeed, but the client reports error:
ORA-12520, TNS:listener could not find available handler for requested type of server
The nodes scan listener log reports the TNS error, listener_scan1/alert/log.xml, when the connection is using TCPS on port 2484:
<msg time='2015-04-29T14:06:20.629-04:00' org_id='oracle' comp_id='tnslsnr'  type='UNKNOWN' level='16' host_id='dublr059vm.dub.usoh.ibm.com'  host_addr='9.55.59.45'>
<txt>29-APR-2015 14:06:20 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=tcarlson))
(SERVER=DEDICATED)(SERVICE_NAME=DUB11RAC)) * (ADDRESS=(PROTOCOL=tcps)(HOST=9.55.61.122)(PORT=46635)) *
establish * DUB11RAC * 12520
</txt>
</msg>
<msg time='2015-04-29T14:06:20.629-04:00' org_id='oracle' comp_id='tnslsnr'
type='UNKNOWN' level='16' host_id='dublr059vm.dub.usoh.ibm.com'
host_addr='9.55.59.45'>
<txt>TNS-12520: TNS:listener could not find available handler for requested type of server
</txt>
</msg>
A connection using TCP completes without error:
<msg time='2015-04-29T14:42:02.588-04:00' org_id='oracle' comp_id='tnslsnr' type='UNKNOWN' level='16' host_id='dublr059vm.dub.usoh.ibm.com'  host_addr='9.55.59.45'>
<txt>29-APR-2015 14:42:02 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=tcarlson))
(SERVER=DEDICATED)(SERVICE_NAME=DUB11RAC)) * (ADDRESS=(PROTOCOL=tcp)(HOST=9.55.61.122)(PORT=41950)) *
establish * DUB11RAC * 0
</txt>
</msg>
The scan listener is configured for TCP on 1521 and TCPS on 2484
[oracle@dublr059vm ~]$ srvctl status scan_listener
SCAN Listener LISTENER_SCAN1 is enabled
SCAN listener LISTENER_SCAN1 is running on node dublr060vm
[oracle@dublr059vm ~]$ srvctl config scan_listener
SCAN Listener LISTENER_SCAN1 exists. Port: TCP:1521/TCPS:2484
The service, dub11rac is ready on both instances.
[oracle@dublr060vm ~]$ lsnrctl stat LISTENER_SCAN1
LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 30-APR-2015 11:45:18
Copyright (c) 1991, 2013, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1)))
STATUS of the LISTENER
Alias                     LISTENER_SCAN1
Version                   TNSLSNR for Linux: Version 11.2.0.4.0 - Production
Start Date                30-APR-2015 11:43:24
Uptime                    0 days 0 hr. 1 min. 53 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/11.2.0/grid/network/admin/listener.ora
Listener Log File         /u01/app/11.2.0/grid/log/diag/tnslsnr/dublr060vm/listener_scan1/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN1)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=9.55.59.47)(PORT=2484)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=9.55.59.47)(PORT=1521)))
Services Summary...
Service "dub11rac" has 2 instance(s).
  Instance "dub11rac1", status READY, has 1 handler(s) for this service...
  Instance "dub11rac2", status READY, has 1 handler(s) for this service...
Service "dub11racXDB" has 2 instance(s).
  Instance "dub11rac1", status READY, has 1 handler(s) for this service...
  Instance "dub11rac2", status READY, has 1 handler(s) for this service...
The command completed successfully

Answer 1

Hi hitgon,
Thanks first.
The commands output are as the following:
Command: srvctl status listener
Output:
# Listener LISTENER is enabled
# Listener LISTENER is running on node(s): rac1,rac2
Command: srvctl status scan_listener
Output:
# SCAN Listener LISTENER_SCAN1 is enabled
# SCAN listener LISTENER_SCAN1 is running on node rac2
# TNSNAMES.ORA
RAC =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-scan)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = rac.localdomain)
Command: sqlplus username/passwd@rac-scan:1521/rac.localdomain
Output:
# ERROR:
# ORA-12520: TNS:listener could not find available handler for requested type of server
# Enter user-name:
By the way, rac-scan is the host where the SCAN listener is running and rac.localdomain is the service name. I've also tried the following commands
with the same error output:
sqlplus username/passwd@RAC
At last, i think the output of "lsnrctl status LISTENER_SCAN1" might help:
Service "rac.localdomain" has 2 instance(s).
Instance "rac1", status READY, has 1 handler(s) for this service...
Instance "rac2", status READY, has 1 handler(s) for this service...
Service "racXDB.localdomain" has 2 instance(s).
Instance "rac1", status READY, has 1 handler(s) for this service...
Instance "rac2", status READY, has 1 handler(s) for this service...