Marko,
I see you are now set to use ojdbc6.jar with DBSolo5 (see below).
If not too much of a hassle for you, I would strongly suggest to use the new ojdbc7.jar , which is the new 12C (and earlier) compatible driver. We have been utilizing ojdbc7.jar for our product/s (tested) against 10gR2 , 11gR2 or 12c and have zero issue so far.
Given Oracle Corp. is pushing big time for the 12C, it would be nice to have 100 % compatibility against Oracle 12C by utilizing the ojdbc7.jar
Just a recommendation.
Zafer
root@raisin:/opt/dbsolo5# ls
commandLine dbsolo DB Solo 5.desktop help image jre lib license_agreements templates uninstall
root@raisin:/opt/dbsolo5# cd lib
root@raisin:/opt/dbsolo5/lib# ls
bc.jar glazedlists.jar jdiff.jar jts.jar looks.jar oids.txt orai18n.jar sqlite-jdbc.jar
db2jcc.jar jalopy.jar jide-oss.jar l2f.jar mysql.jar ojdbc6.jar poi.jar xdb6.jar
freemarker.jar jconn3.jar jtds.jar log4j.jar ofjar.jar openide-util.jar postgres.jar xmlparserv2.jar
root@raisin:/opt/dbsolo5/lib#