OEM 13cR3 - Changing OMS Password (Connection to the repository failed)

Let's say one good day you are trying to restart and OMS and you find this as your error 

Oracle Management Server is not functioning because of the following reason:
Connection to the repository failed. Verify that the repository connection information provided is correct.

Check EM Server log file for details: /u01/app/oracle/em13cr3/gc_inst/user_projects/domains/GCDomain/servers/EMGC_OMS1/logs/EMGC_OMS1.out

And in the EMGC_OMS1.out you will see something like this - 

Invalid Connection Pool. ERROR = ORA-01017: invalid username/password; logon denied


Now what do you do ? 
Simple change the password to your repo 

How ?  Run Below

$ /u01/app/oracle/em13cr3/middleware/bin/emctl config oms -change_repos_pwd -use_sys_pwd -sys_pwd oracle -new_pwd oracle123

Where?
-sys_pwd is followed by existing sysdba password
-new_pwd is followed by new sysman password 


Oracle Enterprise Manager Cloud Control 13c Release 3
Copyright (c) 1996, 2018 Oracle Corporation.  All rights reserved.

Changing passwords in backend ...
Passwords changed in backend successfully.
Updating repository password in Credential Store...
Successfully updated Repository password in Credential Store.
Restart all the OMSs using 'emctl stop oms -all' and 'emctl start oms'.

Successfully changed repository password.

Next as the steps say - and start your OMS
$ emctl stop oms -all
$ emctl start oms