So you may need to migrate customMessages.xml to your new 12c environment. Fortunately, there are a few easy steps to achieve this.
As you may have noticed, OBIEE 12c just came out. I have decided to deinstall 126.96.36.199 completely and install OBIEE 188.8.131.52.0 on my laptop. Things wasn’t so smooth to begin with as I skipped all the documentation. During my installation, I found out that I will need Oracle DB 184.108.40.206+ to begin with, hence I deinstalled my Oracle DB as well.
In order to follow my tutorial, you will need the following downloaded:
Once you have downloaded everything, you can continue reading.