Hi all,
So I was having this issue from a Database Home page on OEM 13c:

Actually, OMS log was presenting several null pointer exceptions… So, whats is the deal?

Everything seemed to match to MOS Bug 22957131 – OEM13C: Exception while loading RAC Database Home Page: null.

The solution?
– Patch 25197714 for the EM 13.2 OMS
– Patch 25155095 for the EM 13.1 OMS

Also, those fixes are included on following Boudle Patches:
– 13.2.1.0.161231
– 13.1.1.0.161220

Applied the patch and solved my case. Hope it helps you!

More Reference:
– EM 13C: Target Database Home Page Displays Message in Enterprise Manager 13c Cloud Control: Regions that display real-time data will not be displayed. Exception while loading RAC Database Home Page: null (Doc ID 2210123.1)
– Note 2219797.1 Enterprise Manager 13.2 Master Bundle Patch List
– Note 2124038.1 Enterprise Manager 13.1 Master Bundle Patch List for the Management Agent and Plug-ins