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Thanks for this offer method https://www.2cto.com/database/201503/378861.html

I'm just doing a detailed explanation. First look at the following is unable to login interface, although there is a user name, password, but no matter what you input, you are prompted by the user name or password error.

Here is the original text, I marked in red.

Can't login em, execute emca-config dbcontrol db do not know always default 1522 port number, helpless, Google some, from the second step below to start execution ... (My monitor is fine)

1. Open the net config Assistant in the Oracle Configuration tool, select "Listener Configuration", Next, then "reconfigure", next, take a closer look at the parameters of each step configuration is OK.

Normal use of data, this step can not be done. But to know your database listening port is which, my change, is 15210.
2. Use the "Emca-deconfig Dbcontrol DB" command on the command line to remove the configuration

Where is this order? I started thinking that it was SQL Plus, and running inside it found no such command. Originally, in the simplest cmd inside, really think too much. There are not too many problems with running this step.
3. Delete repository using "emca-repos drop" command

The main problem in this step, do not understand the port to fill refers to the listening port, thought to be the access port of EM, resulting in a few unsuccessful.

In fact, there is nothing difficult, is to fill the database to manage the SID, is generally ORCL, you have multiple databases or have to be renamed to fill in the actual. Next is the input listener port number, mine is 15210, unchanged should be 1521. Or something else you changed.

Then is the database password, this can not remember the way.
Note: 2nd, 3 steps to do, or in the re-installation of EM will be reported "Ora-20001:sysman already exists." Error caused the installation to fail.

4. Use "Emca-config dbcontrol db-repos Create" command for creating EM.

This is nothing, the database SID and the listener port number is the same, notify the e-mail address these can be directly press ENTER to skip.
After the above steps have been completed successfully created a good EM, click on the Start menu in the Oracle folder in the database CONTROL-ORCL connection can be normal access to EM.
It is important to note that the address of the access EM was https://localhost:1158/em when I first installed Oracle, the port number is 1158, and now the port number behind the address link after I rebuilt em is changed to 5500.

I found that my 1158 did not change, do not know what reason, but finally succeeded. Finally, see the correct page:

Good luck, eat chicken at night!

The database is closed. Please specify host authentication to access database restart and diagnostic tools