I was playing with converting an existing Oracle database to pluggable database and to plug it in the container database. Earlier I had created that non-CDB or in other words the good old database in 12c without any options like APEX etc.
Before plugging this non-CDB database into the CDB, I checked the compatibility and it said 'No'.
Before plugging this non-CDB database into the CDB, I checked the compatibility and it said 'No'.