DLP v14 now Supports/runs with Oracle 188.8.131.52 or 12c Enterprise
Thus, from DLP 12.5.3 (Oracle 184.108.40.206) you need to update Oracle to 220.127.116.11 (if not upgraded already). After you have upgraded Oracle to 18.104.22.168 you can proceed to upgrade to DLP v14.0
So to summarize:
Update Oracle 22.214.171.124 --> Oracle 126.96.36.199 (4-6 hours) --> Upgrade DLP to v14.0 (2 hours) --> Upgrade DLP to v14.5 (2 hours) --> Upgrade DLP to v14.6 (2 hours)
Note: Timelines may vary depending on hardware, database size, backup strategy, etc.
Ideally, we need to update the Enforce first, then the Dectection Server followed by Agents & Scanners.
During most upgrades automatic update feature fails due to the complexity involved - you could use the below link to trigger a manual upgrade, if that happens:
Enforce Manual Upgrade:
Detection Manual Upgrade:
Ofcourse, you would need to backup the Oracle DB and Enforce before proceeding. The below article is for 14.x, but the process remains the same: