Connection problem after a big impdp
Basically your database has stalled because it has ran out of space to store archive logs, and needs to switch one.

To remedy, delete the generated logs (assuming you don't need them for backup and recovery purposes), then execute (as SYSDBA):

alter system archive log all;

alter system switch logfile;


If you don't need to run your database in archivelog mode (ie: you don't need to be able to do any disaster recovery &amp; don't care if your data goes AWOL), you can turn archivelog mode off (as SYSDBA, database in MOUNT mode):

alter database noarchivelog;

alter database open;