I have Oracle database server version 220.127.116.11 installed. Now the requirement is to upgrade it to 18.104.22.168. It has been upgraded using Oracle patch installation. Now the database is shut down and it is started in migrate mode. The problem is even after running the catpatch.sql and utlrp.sql I am facing problems in exporting the data using exp utility. I have also confirmed the upgrade of exp utility to the new version. Please suggest some solution. Also, why is it necessary to start the database in migrate mode?
You only have to start the database in migrate mode once, to run the catpatch.sql script. After that script is done, shut down the database and start it as you normally would.
When in migrate mode, you should not be able to do things like export the database. I expect after you start the database normally, your export should work just fine.