The Oracle monitor is not working / The Oracle monitor is not collecting any data. What can I do?

The Oracle monitor is not working / The Oracle monitor is not collecting any data. What can I do?

Reason 1 - 

This could be because the Oracle user provided in Applications Manager does not have the necessary permission to run the query

Go to <AppManager/logs> directory and check if you have an error print in stderr.txt / stderr.txt.1 / stderr.txt.2 ...  files
SYS_ERR: java.sql.SQLException: ORA-00942: table or view does not exist

If you see the above error, Connect to the Oracle database using the same credentials provided in Applications Manager and execute the below query and check the output:
select VERSION, STARTUP_TIME from v$instance

If you receive the same error (ORA-00942: table or view does not exist), it means Oracle user provided in Applications Manager does not have access to the table or view and you will need to have the owner of the table/view. Refer https://desk.zoho.com/portal/manageengine/kb/articles/i-tried-adding-oracle-monitor-not-able-to-add-it-says-permission-denied for providing required privileges.