Database Preparation Guidelines for an E-Business Suite Release 12.2 Upgrade (Doc ID 1349240.1)
Complete Checklist for Upgrading to Oracle Database 12c Release 1 using DBUA (Doc ID 1516557.1)
Interoperability Notes Oracle EBS 12.2 with Oracle Database 12c Release 1 (Doc ID 1926201.1)
You can also upgrade the database first to 12c using the below document and then upgrade the application to 12.2.4.
Interoperability Notes EBS 12.0 or 12.1 with RDBMS 12cR1 (Doc ID 1524398.1)
What is your 11g database version
The minimum required version to upgrade to 12c is 184.108.40.206.0