Start Enterprise Dashboard and getting this error:
2018-12-10 21:37:31,702Z (13:37) [main] ERROR org.apache.tomcat.jdbc.pool.ConnectionPool - Unable to create initial connections of pool. java.sql.SQLException: ORA-00257: archiver error. Connect internal only, until freed.
A very common Oracle database error that is basically telling you that you have run out of logical or physical space on the mount, disk, or your db_recovery_file_dest location that holds your archivelogs. When you get this error your database hangs and will not allow anyone besides admin level users to log into the database to perform maintenance to fix the problem.
DBA will need to fix this error.