Basically, this error may happened on you haven't privilege to use EM Express, therefore, you should grant "EM_EXPRESS_BASIC" or "EM_EXPRESS_ALL" role to the specified user.
In general, "EM_EXPRESS_BASIC" has been granted to "EM_EXPRESS_ALL" by default and the DBA role include "EM_EXPRESS_ALL".
"EM_EXPRESS_ALL" grants a user all privileges required to perform any action in EM Express.
SQL> column grantee format a20
SQL> select grantee, granted_role from dba_role_privs where granted_role = 'EM_EXPRESS_ALL';
GRANTEE GRANTED_ROLE
-------------------- --------------
DBA EM_EXPRESS_ALL
SYS EM_EXPRESS_ALL
SQL> GRANT EM_EXPRESS_ALL TO SYSTEM;
Grant succeeded.
SQL> select grantee, granted_role from dba_role_privs where granted_role = 'EM_EXPRESS_ALL';
GRANTEE GRANTED_ROLE
-------------------- --------------
SYSTEM EM_EXPRESS_ALL
DBA EM_EXPRESS_ALL
SYS EM_EXPRESS_ALL
SQL>
After that, when you login again as system on EM Express, you can successfully to view the database instance performance. If you still got the security errors, please try use another browsers.
Reference:
