Cannot access EM Express on DB 12c

After install and configure database 12c successfully, you cannot access EM Express 12c. You can check steps below to resolve this issue:
1. Check listener to ensure current listener has EM Express port (Ex: 5500)
lsnrctl status |grep HTTP
It should be return:
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=yourhost.yourdomain)(PORT=5500))(Security=(my_wallet_directory=/u01/app/oracle/product/12.1/db_1/admin/PROD/xdb_wallet))(Presentation=HTTP)(Session=RAW))

2. Check port 5500 by telnet client
telnet 5500

3. Check permission in xdb_wallet folder:
cd /u01/app/oracle/product/12.1/db_1/admin/PROD/xdb_wallet
ls -l
-rw——- 1 oracle oinstall 3862 Sep 6 19:47 cwallet.sso
-rw——- 1 oracle oinstall 3817 Sep 6 19:47 ewallet.p12
It is not correct permission. You need to change mode for these files.
chmod 640 *
Check again:
ls -l
-rw-r—– 1 oracle oinstall 3862 Sep 6 19:47 cwallet.sso
-rw-r—– 1 oracle oinstall 3817 Sep 6 19:47 ewallet.p12

Try to connect EM Express 12c from web browser has Flash installed. It should be connect successful.

Reference: Troubleshooting Why EM Express is not Working (Doc ID 1604062.1)

Topic: 10- Wallet file permissions when RDBMS sits on top of GI with role separation: