I am sorry if this has already been answered previously but I have already spent an hour seraching the forums for an answer and can't waste any more time searching.
As the topic of this disucssion states I am able to login as "sys as sysdba" using sqlplus but EOM login using the same credentials fails. Oracle database version is 11g-r2. Operation system is Windows Server 2008. I am accessing the server via directly through Remote Desktop Connection.
It could be that the SYSMAN password has expired but the behavior I am currently experiencing is very different from any former experience which is that the login succeeds but connection to the database fails (it has always been so) so I believe this is a different problem.
executing [sqlplus sys@<tns_alias> as sysdba] is successful
When I try to login on to OEM the login page reappears with the message "Your username and password are invalid"
My login procedure is to type "sys" as username, the password in the password box and select SYSDBA from the drop-down list.
Changed the SYS password to something simple and login succeeded. Changed it back to what I had before and login succeeded.
I really can't believe that I typed the password wrong in over 15 tries when I use (almost) the same password in many other places and have no such problems, expecially seeing that I did use the password several times for sqlplus and did not make a mistake once.
Anyway it seems to be working now for some reason.
Thanks for the tips.
You can bookmark the below doc which talks in detail how to troubleshoot such errors in case you encounter them in future
EM 12c : Unable Login To Target Database " ORA-01017: invalid username/password; logon denied " Error Returned (Doc ID 1521695.1)