ORA-28365: wallet is not open while starting the Database

$ srvctl start instance -d CDB -i CDB01

PRCR-1013 : Failed to start resource ora.cdb.db
PRCR-1064 : Failed to start resource ora.cdb.db on node node1.oracle.com
CRS-5017: The resource action "ora.cdb.db start" encountered the following error:
ORA-28365: wallet is not open
. For details refer to "(:CLSN00107:)" in "/u01/app/oracle/diag/crs/node1.oracle.com/crs/trace/crsd_oraagent_oracle.trc".
CRS-2674: Start of 'ora.cdb.db' on 'node1.oracle.com' failed

Solution:
Start the instance in mount mode
SQL> startup mount;
ORACLE instance started.
Total System Global Area 2147483648 bytes
Fixed Size                  2926472 bytes
Variable Size            1392511096 bytes
Database Buffers          738197504 bytes
Redo Buffers               13848576 bytes
Database mounted.

Check wallet status

set linesize 200
col WALLET_DIR for a32
col status for a21

select STATUS,WRL_PARAMETER WALLET_DIR,WALLET_TYPE from V$ENCRYPTION_WALLET;
STATUS                WALLET_DIR                       WALLET_TYPE
--------------------- -------------------------------- ------------------------------------------------------------
CLOSED                +DATA1/CDB/wallet/           UNKNOWN

Open the Keystore

SQL> ADMINISTER KEY MANAGEMENT SET KEYSTORE OPEN IDENTIFIED BY "xxxxx";

keystore altered.

Open the database

SQL> alter database open;

Database altered.