Upgrading Open-AudIT from 1.8.4 to 2.2.7

Hi

We are planning migrate to most recent Open-AudIT version in December and I started testing in lab.

Currently we use 1.8.4 on CentOS 6.

We test following these steps:

Create new CentOS 6 VM

Install Open-AudIT 1.8.4

Import DB from production server 

Install Open-AudIT 2.2.7 (until here no error or problem)

When I login to perform the DB conversion "a Database Error Occurred"

Our target is move to most recent version in CentOS 6 and then move a CentOS 7 Server.

Any idea to fix the error?

Thank you!