The application requires more database privileges than you have currently been granted. Click on Help to get more version specific information.
Unfortunately, when you click on HELP, it may not give proper details on which privilege is missing.
When checked at DB level, may be that user will have all the required privileges to connect to the database, but still login to OEM is impacted.
The solution for this is to grant SELECT_CATALOG_ROLE to that user.
sqlplus / as sysdba
SQL> grant select_catalog_role to schemaname;
for example, if you are facing issue with scott schema, then issue below command
SQL> grant select_catalog_role to scott;
After above grant, user should able to login to OEM.
But, even after granting the above role, still if you face issue, then you may need to grant select on dictionary views to that user. But do remember, with this user can able to retrieve dictionary information from oracle database. So, grant it only if it is very much required.
SQL> grant select any dictionary to scott;